diff --git a/App/Client.xcodeproj/xcshareddata/xcschemes/ActionExtension.xcscheme b/App/Client.xcodeproj/xcshareddata/xcschemes/ActionExtension.xcscheme
index 380f4146390..1ade4d922e9 100644
--- a/App/Client.xcodeproj/xcshareddata/xcschemes/ActionExtension.xcscheme
+++ b/App/Client.xcodeproj/xcshareddata/xcschemes/ActionExtension.xcscheme
@@ -73,7 +73,6 @@
       savedToolIdentifier = ""
       useCustomWorkingDirectory = "NO"
       debugDocumentVersioning = "YES"
-      askForAppToLaunch = "Yes"
       launchAutomaticallySubstyle = "2">
       <BuildableProductRunnable
          runnableDebuggingMode = "0">
diff --git a/App/iOS/Delegates/SceneDelegate.swift b/App/iOS/Delegates/SceneDelegate.swift
index 755824de6d5..1e2f97fc0a0 100644
--- a/App/iOS/Delegates/SceneDelegate.swift
+++ b/App/iOS/Delegates/SceneDelegate.swift
@@ -243,7 +243,9 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
       AppState.shared.dau.sendPingToServer()
     }
     
-    BraveSkusManager.refreshSKUCredential(isPrivate: scene.browserViewController?.privateBrowsingManager.isPrivateBrowsing == true)
+    Task { @MainActor in
+      await BraveSkusManager.refreshSKUCredential(isPrivate: scene.browserViewController?.privateBrowsingManager.isPrivateBrowsing == true)
+    }
   }
 
   func sceneWillResignActive(_ scene: UIScene) {
diff --git a/Sources/Brave/BraveSkus/BraveSkusManager.swift b/Sources/Brave/BraveSkus/BraveSkusManager.swift
index 9349b20cb38..c3d95b057d1 100644
--- a/Sources/Brave/BraveSkus/BraveSkusManager.swift
+++ b/Sources/Brave/BraveSkus/BraveSkusManager.swift
@@ -10,6 +10,7 @@ import BraveCore
 import BraveVPN
 import os.log
 
+@MainActor
 public class BraveSkusManager {
   private let sku: SkusSkusService
   
@@ -22,7 +23,7 @@ public class BraveSkusManager {
     self.sku = skusService
   }
   
-  public static func refreshSKUCredential(isPrivate: Bool) {
+  public static func refreshSKUCredential(isPrivate: Bool) async {
     guard let _ = Preferences.VPN.skusCredential.value,
           let domain = Preferences.VPN.skusCredentialDomain.value,
           let expirationDate = Preferences.VPN.expirationDate.value else {
@@ -39,98 +40,93 @@ public class BraveSkusManager {
       return
     }
     
-    manager.credentialSummary(for: domain) { completion in
-      Logger.module.debug("credentialSummary response")
-    }
+    _ = await manager.credentialSummary(for: domain)
+    Logger.module.debug("credentialSummary response")
   }
   
   // MARK: - Handling SKU methods.
   
-  func refreshOrder(for orderId: String, domain: String, resultJSON: @escaping (Any?) -> Void) {
-    sku.refreshOrder(domain, orderId: orderId) { completion in
-      do {
-        guard let data = completion.data(using: .utf8) else { return }
-        let json = try JSONSerialization.jsonObject(with: data, options: .fragmentsAllowed)
-        Logger.module.debug("refreshOrder json parsed successfully")
-        resultJSON(json)
-      } catch {
-        resultJSON(nil)
-        Logger.module.error("refrshOrder: Failed to decode json: \(error.localizedDescription)")
-      }
+  func refreshOrder(for orderId: String, domain: String) async -> Any? {
+    let response = await sku.refreshOrder(domain, orderId: orderId)
+    
+    do {
+      guard let data = response.data(using: .utf8) else { return nil }
+      let json = try JSONSerialization.jsonObject(with: data, options: .fragmentsAllowed)
+      Logger.module.debug("refreshOrder json parsed successfully")
+      return json
+    } catch {
+      Logger.module.error("refrshOrder: Failed to decode json: \(error.localizedDescription)")
+      return nil
     }
   }
   
-  func fetchOrderCredentials(for orderId: String, domain: String, resultCredential: @escaping (String) -> Void) {
-    sku.fetchOrderCredentials(domain, orderId: orderId) { completion in
-      Logger.module.debug("skus fetchOrderCredentials")
-      resultCredential(completion)
-    }
+  func fetchOrderCredentials(for orderId: String, domain: String) async -> String {
+    let credential = await sku.fetchOrderCredentials(domain, orderId: orderId)
+    Logger.module.debug("skus fetchOrderCredentials")
+    return credential
   }
   
-  func prepareCredentialsPresentation(for domain: String, path: String,
-                                      resultCredential: ((String) -> Void)?) {
+  func prepareCredentialsPresentation(for domain: String, path: String) async -> String {
     Logger.module.debug("skus prepareCredentialsPresentation")
-    sku.prepareCredentialsPresentation(domain, path: path) { credential in
-      if !credential.isEmpty {
-        if let vpnCredential = BraveSkusWebHelper.fetchVPNCredential(credential, domain: domain) {
-          Preferences.VPN.skusCredential.value = credential
-          Preferences.VPN.skusCredentialDomain.value = domain
-          Preferences.VPN.expirationDate.value = vpnCredential.expirationDate
-          
-          BraveVPN.setCustomVPNCredential(vpnCredential)
-        }
-      } else {
-        Logger.module.debug("skus empty credential from prepareCredentialsPresentation call")
+    
+    let credential = await sku.prepareCredentialsPresentation(domain, path: path)
+    
+    if !credential.isEmpty {
+      if let vpnCredential = BraveSkusWebHelper.fetchVPNCredential(credential, domain: domain) {
+        Preferences.VPN.skusCredential.value = credential
+        Preferences.VPN.skusCredentialDomain.value = domain
+        Preferences.VPN.expirationDate.value = vpnCredential.expirationDate
+        
+        BraveVPN.setCustomVPNCredential(vpnCredential)
       }
-      
-      resultCredential?(credential)
+    } else {
+      Logger.module.debug("skus empty credential from prepareCredentialsPresentation call")
     }
+    
+    return credential
   }
   
-  func credentialSummary(for domain: String, resultJSON: @escaping (Any?) -> Void) {
-    sku.credentialSummary(domain) { [self] completion in
-      do {
-        Logger.module.debug("skus credentialSummary")
-        
-        guard let data = completion.data(using: .utf8) else {
-          resultJSON(nil)
-          return
+  func credentialSummary(for domain: String) async -> Any? {
+    let credential = await sku.credentialSummary(domain)
+    
+    do {
+      Logger.module.debug("skus credentialSummary")
+      
+      guard let data = credential.data(using: .utf8) else {
+        return nil
+      }
+      
+      let json = try JSONSerialization.jsonObject(with: data, options: .fragmentsAllowed)
+      
+      let jsonDecoder = JSONDecoder()
+      jsonDecoder.keyDecodingStrategy = .convertFromSnakeCase
+      let credentialSummaryJson = try jsonDecoder.decode(CredentialSummary.self, from: data)
+      
+      switch credentialSummaryJson.state {
+      case .valid:
+        if Preferences.VPN.skusCredential.value == nil {
+          Logger.module.debug("The credential does NOT exists, calling prepareCredentialsPresentation")
+          _ = await prepareCredentialsPresentation(for: domain, path: "*")
+        } else {
+          Logger.module.debug("The credential exists, NOT calling prepareCredentialsPresentation")
         }
-        let json = try JSONSerialization.jsonObject(with: data, options: .fragmentsAllowed)
-        
-        let jsonDecoder = JSONDecoder()
-        jsonDecoder.keyDecodingStrategy = .convertFromSnakeCase
-        let credentialSummaryJson = try jsonDecoder.decode(CredentialSummary.self, from: data)
-        
-        switch credentialSummaryJson.state {
-        case .valid:
-          if Preferences.VPN.skusCredential.value == nil {
-            Logger.module.debug("The credential does NOT exists, calling prepareCredentialsPresentation")
-            self.prepareCredentialsPresentation(for: domain, path: "*") { _ in
-              // Keep the skus manager alive until preparing credential presentation finishes.
-              _ = self
-            }
-          } else {
-            Logger.module.debug("The credential exists, NOT calling prepareCredentialsPresentation")
-          }
-        case .sessionExpired:
-          Logger.module.debug("This credential session has expired")
-          Self.keepShowingSessionExpiredState = true
-        case .invalid:
-          if !credentialSummaryJson.active {
-            Logger.module.debug("The credential summary is not active")
-          }
-          
-          if credentialSummaryJson.remainingCredentialCount <= 0 {
-            Logger.module.debug("The credential summary does not have any remaining credentials")
-          }
+      case .sessionExpired:
+        Logger.module.debug("This credential session has expired")
+        Self.keepShowingSessionExpiredState = true
+      case .invalid:
+        if !credentialSummaryJson.active {
+          Logger.module.debug("The credential summary is not active")
         }
         
-        resultJSON(json)
-      } catch {
-        resultJSON(nil)
-        Logger.module.error("refrshOrder: Failed to decode json: \(error.localizedDescription)")
+        if credentialSummaryJson.remainingCredentialCount <= 0 {
+          Logger.module.debug("The credential summary does not have any remaining credentials")
+        }
       }
+      
+      return json
+    } catch {
+      Logger.module.error("refrshOrder: Failed to decode json: \(error.localizedDescription)")
+      return nil
     }
   }
   
diff --git a/Sources/Brave/Frontend/Browser/BraveGetUA.swift b/Sources/Brave/Frontend/Browser/BraveGetUA.swift
index 3961b0dcb89..c8f9c7693eb 100644
--- a/Sources/Brave/Frontend/Browser/BraveGetUA.swift
+++ b/Sources/Brave/Frontend/Browser/BraveGetUA.swift
@@ -30,8 +30,9 @@ class BraveGetUA: TabContentScript {
                                in: scriptSandbox)
   }()
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     // 🙀 😭 🏃‍♀️💨
+    return (nil, nil)
   }
 
   static var isActivated: Bool {
diff --git a/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+ReaderMode.swift b/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+ReaderMode.swift
index dc649604492..d505770fb19 100644
--- a/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+ReaderMode.swift
+++ b/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+ReaderMode.swift
@@ -118,8 +118,8 @@ extension BrowserViewController {
   /// and be done with it. In the more complicated case, reader mode was already open for this page and we simply
   /// navigated away from it. So we look to the left and right in the BackForwardList to see if a readerized version
   /// of the current page is there. And if so, we go there.
-
-  func enableReaderMode() {
+  @MainActor
+  func enableReaderMode() async {
     guard let tab = tabManager.selectedTab, let webView = tab.webView else { return }
 
     let backList = webView.backForwardList.backList
@@ -132,11 +132,11 @@ extension BrowserViewController {
     if backList.count > 1 && backList.last?.url == readerModeURL {
       let playlistItem = tab.playlistItem
       webView.go(to: backList.last!)
-      PlaylistScriptHandler.updatePlaylistTab(tab: tab, item: playlistItem)
+      await PlaylistScriptHandler.updatePlaylistTab(tab: tab, item: playlistItem)
     } else if !forwardList.isEmpty && forwardList.first?.url == readerModeURL {
       let playlistItem = tab.playlistItem
       webView.go(to: forwardList.first!)
-      PlaylistScriptHandler.updatePlaylistTab(tab: tab, item: playlistItem)
+      await PlaylistScriptHandler.updatePlaylistTab(tab: tab, item: playlistItem)
     } else {
       // Store the readability result in the cache and load it. This will later move to the ReadabilityHelper.
       webView.evaluateSafeJavaScript(functionName: "\(ReaderModeNamespace).readerize", contentWorld: ReaderModeScriptHandler.scriptSandbox) { (object, error) -> Void in
@@ -144,7 +144,9 @@ extension BrowserViewController {
           let playlistItem = tab.playlistItem
           try? self.readerModeCache.put(currentURL, readabilityResult)
           if webView.load(PrivilegedRequest(url: readerModeURL) as URLRequest) != nil {
-            PlaylistScriptHandler.updatePlaylistTab(tab: tab, item: playlistItem)
+            Task { @MainActor in
+              await PlaylistScriptHandler.updatePlaylistTab(tab: tab, item: playlistItem)
+            }
           }
         }
       }
@@ -155,8 +157,8 @@ extension BrowserViewController {
   /// means that there is nothing in the BackForwardList except the internal url for the reader mode page. In that
   /// case we simply open a new page with the original url. In the more complicated page, the non-readerized version
   /// of the page is either to the left or right in the BackForwardList. If that is the case, we navigate there.
-
-  func disableReaderMode() {
+  @MainActor
+  func disableReaderMode() async {
     if let tab = tabManager.selectedTab,
       let webView = tab.webView {
       let backList = webView.backForwardList.backList
@@ -167,15 +169,15 @@ extension BrowserViewController {
           if backList.count > 1 && backList.last?.url == originalURL {
             let playlistItem = tab.playlistItem
             webView.go(to: backList.last!)
-            PlaylistScriptHandler.updatePlaylistTab(tab: tab, item: playlistItem)
+            await PlaylistScriptHandler.updatePlaylistTab(tab: tab, item: playlistItem)
           } else if !forwardList.isEmpty && forwardList.first?.url == originalURL {
             let playlistItem = tab.playlistItem
             webView.go(to: forwardList.first!)
-            PlaylistScriptHandler.updatePlaylistTab(tab: tab, item: playlistItem)
+            await PlaylistScriptHandler.updatePlaylistTab(tab: tab, item: playlistItem)
           } else {
             let playlistItem = tab.playlistItem
             if webView.load(URLRequest(url: originalURL)) != nil {
-              PlaylistScriptHandler.updatePlaylistTab(tab: tab, item: playlistItem)
+              await PlaylistScriptHandler.updatePlaylistTab(tab: tab, item: playlistItem)
             }
           }
         }
diff --git a/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+ShareActivity.swift b/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+ShareActivity.swift
index 256fc0c5618..4029f0d35db 100644
--- a/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+ShareActivity.swift
+++ b/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+ShareActivity.swift
@@ -73,7 +73,9 @@ extension BrowserViewController {
             title: Strings.toggleReaderMode,
             braveSystemImage: "leo.product.speedreader",
             callback: { [weak self] in
-              self?.toggleReaderMode()
+              Task { @MainActor in
+                await self?.toggleReaderMode()
+              }
             }
           )
         )
diff --git a/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+TabManagerDelegate.swift b/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+TabManagerDelegate.swift
index 73d2657894b..69cca5e7a06 100644
--- a/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+TabManagerDelegate.swift
+++ b/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+TabManagerDelegate.swift
@@ -187,6 +187,8 @@ extension BrowserViewController: TabManagerDelegate {
     if !privateBrowsingManager.isPrivateBrowsing {
       rewards.reportTabClosed(tabId: Int(tab.rewardsId))
     }
+    
+    tab.destroy()
   }
 
   func tabManagerDidAddTabs(_ tabManager: TabManager) {
diff --git a/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+ToolbarDelegate.swift b/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+ToolbarDelegate.swift
index 3dd001f37a8..bb68627c8db 100644
--- a/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+ToolbarDelegate.swift
+++ b/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+ToolbarDelegate.swift
@@ -127,7 +127,9 @@ extension BrowserViewController: TopToolbarDelegate {
   }
 
   func topToolbarDidPressReaderMode(_ topToolbar: TopToolbarView) {
-    toggleReaderMode()
+    Task { @MainActor in
+      await toggleReaderMode()
+    }
   }
 
   func topToolbarDidPressPlaylistButton(_ urlBar: TopToolbarView) {
diff --git a/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+WKNavigationDelegate.swift b/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+WKNavigationDelegate.swift
index 0a58c67f48e..b4efbdd1484 100644
--- a/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+WKNavigationDelegate.swift
+++ b/Sources/Brave/Frontend/Browser/BrowserViewController/BVC+WKNavigationDelegate.swift
@@ -1161,6 +1161,7 @@ extension BrowserViewController: WKUIDelegate {
     webView.evaluateSafeJavaScript(functionName: script, contentWorld: .defaultClient, asFunction: false)
   }
 
+  @MainActor
   func handleAlert<T: JSAlertInfo>(webView: WKWebView, alert: inout T, completionHandler: @escaping () -> Void) {
     guard let promptingTab = tabManager[webView], !promptingTab.blockAllAlerts else {
       suppressJSAlerts(webView: webView)
@@ -1169,9 +1170,10 @@ extension BrowserViewController: WKUIDelegate {
       return
     }
     promptingTab.alertShownCount += 1
+    
     let suppressBlock: JSAlertInfo.SuppressHandler = { [unowned self] suppress in
       if suppress {
-        func suppressDialogues(_: UIAlertAction) {
+        @MainActor func suppressDialogues(_: UIAlertAction) {
           self.suppressJSAlerts(webView: webView)
           promptingTab.blockAllAlerts = true
           self.tabManager[webView]?.cancelQueuedAlerts()
diff --git a/Sources/Brave/Frontend/Browser/BrowserViewController/BrowserViewController.swift b/Sources/Brave/Frontend/Browser/BrowserViewController/BrowserViewController.swift
index 4c9f461078b..4cd550b1e35 100644
--- a/Sources/Brave/Frontend/Browser/BrowserViewController/BrowserViewController.swift
+++ b/Sources/Brave/Frontend/Browser/BrowserViewController/BrowserViewController.swift
@@ -1713,6 +1713,7 @@ public class BrowserViewController: UIViewController {
   // to report internal page load to Rewards lib
   var rewardsXHRLoadURL: URL?
 
+  @MainActor
   override public func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey: Any]?, context: UnsafeMutableRawPointer?) {
 
     guard let webView = object as? WKWebView else {
@@ -1945,8 +1946,10 @@ public class BrowserViewController: UIViewController {
       
       Task { @MainActor in
         do {
-          let result = await BraveCertificateUtils.verifyTrust(serverTrust, host: host, port: port)
-          
+          let result = BraveCertificateUtility.verifyTrust(serverTrust,
+                                                           host: host,
+                                                           port: port)
+
           // Cert is valid!
           if result == 0 {
             tab.secureContentState = .secure
@@ -2331,14 +2334,15 @@ public class BrowserViewController: UIViewController {
     }
   }
   
-  func toggleReaderMode() {
+  @MainActor
+  func toggleReaderMode() async {
     guard let tab = tabManager.selectedTab else { return }
     if let readerMode = tab.getContentScript(name: ReaderModeScriptHandler.scriptName) as? ReaderModeScriptHandler {
       switch readerMode.state {
       case .available:
-        enableReaderMode()
+        await enableReaderMode()
       case .active:
-        disableReaderMode()
+        await disableReaderMode()
       case .unavailable:
         break
       }
diff --git a/Sources/Brave/Frontend/Browser/FaviconHandler.swift b/Sources/Brave/Frontend/Browser/FaviconHandler.swift
index 72b69ea362a..3dcd06ede90 100644
--- a/Sources/Brave/Frontend/Browser/FaviconHandler.swift
+++ b/Sources/Brave/Frontend/Browser/FaviconHandler.swift
@@ -23,6 +23,7 @@ class FaviconHandler {
     unregister(tabObservers)
   }
 
+  @MainActor
   func loadFaviconURL(
     _ url: URL,
     forTab tab: Tab
@@ -34,6 +35,7 @@ class FaviconHandler {
 }
 
 extension FaviconHandler: TabEventHandler {
+  @MainActor
   func tab(_ tab: Tab, didLoadPageMetadata metadata: PageMetadata) {
     if let currentURL = tab.url {
       if let favicon = FaviconFetcher.getIconFromCache(for: currentURL) {
diff --git a/Sources/Brave/Frontend/Browser/FingerprintingProtection.swift b/Sources/Brave/Frontend/Browser/FingerprintingProtection.swift
index 1f794f1de62..93852b4c561 100644
--- a/Sources/Brave/Frontend/Browser/FingerprintingProtection.swift
+++ b/Sources/Brave/Frontend/Browser/FingerprintingProtection.swift
@@ -30,11 +30,12 @@ class FingerprintingProtection: TabContentScript {
                         in: scriptSandbox)
   }()
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
+  @MainActor
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if let stats = self.tab?.contentBlocker.stats {
       self.tab?.contentBlocker.stats = stats.adding(fingerprintingCount: 1)
       BraveGlobalShieldStats.shared.fpProtection += 1
     }
+    return (nil, nil)
   }
 }
diff --git a/Sources/Brave/Frontend/Browser/FrequencyQuery.swift b/Sources/Brave/Frontend/Browser/FrequencyQuery.swift
index 024aa17e974..5cc832ef67e 100644
--- a/Sources/Brave/Frontend/Browser/FrequencyQuery.swift
+++ b/Sources/Brave/Frontend/Browser/FrequencyQuery.swift
@@ -75,6 +75,7 @@ class FrequencyQuery {
     }
   }
     
+  @MainActor
   private func fetchSitesFromTabs(_ tabs: [Tab]) -> [Site] {
     var tabList = [Site]()
         
diff --git a/Sources/Brave/Frontend/Browser/Helpers/BrowserNavigationHelper.swift b/Sources/Brave/Frontend/Browser/Helpers/BrowserNavigationHelper.swift
index 5b58563ff6b..e87e166286f 100644
--- a/Sources/Brave/Frontend/Browser/Helpers/BrowserNavigationHelper.swift
+++ b/Sources/Brave/Frontend/Browser/Helpers/BrowserNavigationHelper.swift
@@ -74,6 +74,7 @@ class BrowserNavigationHelper {
     open(vc, doneButton: DoneButton(style: .done, position: .left))
   }
 
+  @MainActor
   func openShareSheet() {
     guard let bvc = bvc else { return }
     dismissView()
diff --git a/Sources/Brave/Frontend/Browser/Helpers/MetadataParserHelper.swift b/Sources/Brave/Frontend/Browser/Helpers/MetadataParserHelper.swift
index b895e934496..f637708749b 100644
--- a/Sources/Brave/Frontend/Browser/Helpers/MetadataParserHelper.swift
+++ b/Sources/Brave/Frontend/Browser/Helpers/MetadataParserHelper.swift
@@ -21,6 +21,7 @@ class MetadataParserHelper: TabEventHandler {
     unregister(tabObservers)
   }
 
+  @MainActor
   func tab(_ tab: Tab, didChangeURL url: URL) {
     // Get the metadata out of the page-metadata-parser, and into a type safe struct as soon
     // as possible.
diff --git a/Sources/Brave/Frontend/Browser/Helpers/ScreenshotHelper.swift b/Sources/Brave/Frontend/Browser/Helpers/ScreenshotHelper.swift
index a89c01b8186..6695cb0312f 100644
--- a/Sources/Brave/Frontend/Browser/Helpers/ScreenshotHelper.swift
+++ b/Sources/Brave/Frontend/Browser/Helpers/ScreenshotHelper.swift
@@ -20,6 +20,7 @@ class ScreenshotHelper {
     self.tabManager = tabManager
   }
 
+  @MainActor
   func takeScreenshot(_ tab: Tab) {
     guard let webView = tab.webView, let url = tab.url else {
       Logger.module.error("Tab webView or url is nil")
@@ -70,6 +71,7 @@ class ScreenshotHelper {
     }
   }
 
+  @MainActor
   func takePendingScreenshots(_ tabs: [Tab]) {
     for tab in tabs where tab.pendingScreenshot {
       tab.pendingScreenshot = false
diff --git a/Sources/Brave/Frontend/Browser/LinkPreviewViewController.swift b/Sources/Brave/Frontend/Browser/LinkPreviewViewController.swift
index aaa1afb1798..1336eab6348 100644
--- a/Sources/Brave/Frontend/Browser/LinkPreviewViewController.swift
+++ b/Sources/Brave/Frontend/Browser/LinkPreviewViewController.swift
@@ -61,7 +61,9 @@ class LinkPreviewViewController: UIViewController {
   }
   
   deinit {
-    self.currentTab?.navigationDelegate = nil
-    self.currentTab = nil
+    Task { @MainActor in
+      self.currentTab?.navigationDelegate = nil
+      self.currentTab = nil
+    }
   }
 }
diff --git a/Sources/Brave/Frontend/Browser/NavigationRouter.swift b/Sources/Brave/Frontend/Browser/NavigationRouter.swift
index 29706cdf34a..273b58a241a 100644
--- a/Sources/Brave/Frontend/Browser/NavigationRouter.swift
+++ b/Sources/Brave/Frontend/Browser/NavigationRouter.swift
@@ -15,6 +15,7 @@ public enum DeepLink: String {
 }
 
 // The root navigation for the Router. Look at the tests to see a complete URL
+@MainActor
 public enum NavigationPath: Equatable {
   case url(webURL: URL?, isPrivate: Bool)
   case deepLink(DeepLink)
diff --git a/Sources/Brave/Frontend/Browser/PageZoom/PageZoomHandler.swift b/Sources/Brave/Frontend/Browser/PageZoom/PageZoomHandler.swift
index f727685131a..102c5ee9e30 100644
--- a/Sources/Brave/Frontend/Browser/PageZoom/PageZoomHandler.swift
+++ b/Sources/Brave/Frontend/Browser/PageZoom/PageZoomHandler.swift
@@ -8,6 +8,7 @@ import Shared
 import Data
 import Preferences
 
+@MainActor
 class PageZoomHandler: ObservableObject {
   
   enum ChangeStatus {
diff --git a/Sources/Brave/Frontend/Browser/Playlist/Controllers/PlaylistCarplayController.swift b/Sources/Brave/Frontend/Browser/Playlist/Controllers/PlaylistCarplayController.swift
index 6a6db325390..09184c5feaf 100644
--- a/Sources/Brave/Frontend/Browser/Playlist/Controllers/PlaylistCarplayController.swift
+++ b/Sources/Brave/Frontend/Browser/Playlist/Controllers/PlaylistCarplayController.swift
@@ -27,6 +27,7 @@ enum PlaylistCarplayError: Error {
   case itemExpired(id: String)
 }
 
+@MainActor
 class PlaylistCarplayController: NSObject {
   private let player: MediaPlayer
   private let mediaStreamer: PlaylistMediaStreamer
diff --git a/Sources/Brave/Frontend/Browser/Playlist/Controllers/PlaylistViewController.swift b/Sources/Brave/Frontend/Browser/Playlist/Controllers/PlaylistViewController.swift
index 3f33415fb24..c78bd3beced 100644
--- a/Sources/Brave/Frontend/Browser/Playlist/Controllers/PlaylistViewController.swift
+++ b/Sources/Brave/Frontend/Browser/Playlist/Controllers/PlaylistViewController.swift
@@ -99,11 +99,11 @@ class PlaylistViewController: UIViewController {
     if let item = PlaylistCarplayManager.shared.currentPlaylistItem {
       updateLastPlayedItem(item: item)
     }
-
+    
     // Stop picture in picture
     player.pictureInPictureController?.delegate = nil
     player.pictureInPictureController?.stopPictureInPicture()
-
+    
     // Simulator cannot "detect" if Car-Play is enabled, therefore we need to STOP playback
     // When this controller deallocates. The user can still manually resume playback in CarPlay.
     if !PlaylistCarplayManager.shared.isCarPlayAvailable {
@@ -111,16 +111,19 @@ class PlaylistViewController: UIViewController {
       stop(playerView)
       PlaylistCarplayManager.shared.currentPlaylistItem = nil
       PlaylistCarplayManager.shared.currentlyPlayingItemIndex = -1
-
+      
       // Destroy folder observers
       folderObserver = nil
       PlaylistManager.shared.currentFolder = nil
     }
-
+    
     // Cancel all loading.
     listController.stopLoadingSharedPlaylist()
     PlaylistManager.shared.playbackTask = nil
-    PlaylistCarplayManager.shared.playlistController = nil
+    
+    Task { @MainActor in
+      PlaylistCarplayManager.shared.playlistController = nil
+    }
   }
 
   override func viewDidLoad() {
diff --git a/Sources/Brave/Frontend/Browser/Playlist/Managers & Cache/PlaylistCacheLoader.swift b/Sources/Brave/Frontend/Browser/Playlist/Managers & Cache/PlaylistCacheLoader.swift
index 97cb1b376f4..01edc3e63f4 100644
--- a/Sources/Brave/Frontend/Browser/Playlist/Managers & Cache/PlaylistCacheLoader.swift	
+++ b/Sources/Brave/Frontend/Browser/Playlist/Managers & Cache/PlaylistCacheLoader.swift	
@@ -17,11 +17,13 @@ import os.log
 import Playlist
 
 class LivePlaylistWebLoaderFactory: PlaylistWebLoaderFactory {
+  @MainActor
   func makeWebLoader() -> PlaylistWebLoader {
     LivePlaylistWebLoader()
   }
 }
 
+@MainActor
 class LivePlaylistWebLoader: UIView, PlaylistWebLoader {
   fileprivate static var pageLoadTimeout = 300.0
   private var pendingRequests = [String: URLRequest]()
@@ -60,11 +62,6 @@ class LivePlaylistWebLoader: UIView, PlaylistWebLoader {
     fatalError("init(coder:) has not been implemented")
   }
 
-  deinit {
-    self.removeFromSuperview()
-  }
-
-  @MainActor
   func load(url: URL) async -> PlaylistInfo? {
     return await withCheckedContinuation { continuation in
       self.handler = { [weak self] in
@@ -110,24 +107,26 @@ class LivePlaylistWebLoader: UIView, PlaylistWebLoader {
     webView.loadHTMLString("<html><body>PlayList</body></html>", baseURL: nil)
   }
 
+  @MainActor
   private class PlaylistWebLoaderContentHelper: TabContentScript {
     private weak var webLoader: LivePlaylistWebLoader?
     private var playlistItems = Set<String>()
     private var isPageLoaded = false
-    private var timeout: DispatchWorkItem?
+    private var timeout: Task<Void, Error>?
 
     init(_ webLoader: LivePlaylistWebLoader) {
       self.webLoader = webLoader
       
-      timeout = DispatchWorkItem(block: { [weak self] in
-        guard let self = self else { return }
+      timeout = Task.delayed(bySeconds: LivePlaylistWebLoader.pageLoadTimeout) { @MainActor in
         self.webLoader?.handler?(nil)
         self.webLoader?.tab.webView?.loadHTMLString("<html><body>PlayList</body></html>", baseURL: nil)
         self.webLoader = nil
-      })
-
+      }
+      
       if let timeout = timeout {
-        DispatchQueue.main.asyncAfter(deadline: .now() + LivePlaylistWebLoader.pageLoadTimeout, execute: timeout)
+        Task {
+          _ = try? await timeout.value
+        }
       }
     }
 
@@ -138,14 +137,13 @@ class LivePlaylistWebLoader: UIView, PlaylistWebLoader {
     static let userScript: WKUserScript? = nil
     static let playlistProcessDocumentLoad = PlaylistScriptHandler.playlistProcessDocumentLoad
 
-    func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
+    @MainActor
+    func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
       if !verifyMessage(message: message) {
         assertionFailure("Missing required security token.")
-        return
+        return (nil, nil)
       }
       
-      replyHandler(nil, nil)
-      
       let cancelRequest = {
         self.timeout?.cancel()
         self.timeout = nil
@@ -159,54 +157,56 @@ class LivePlaylistWebLoader: UIView, PlaylistWebLoader {
         
         if readyState.state == "cancel" {
           cancelRequest()
-          return
+          return (nil, nil)
         }
           
         if isPageLoaded {
           timeout?.cancel()
-          timeout = DispatchWorkItem(block: { [weak self] in
-            guard let self = self else { return }
+          timeout = Task.delayed(bySeconds: LivePlaylistWebLoader.pageLoadTimeout) { @MainActor in
             self.webLoader?.handler?(nil)
             self.webLoader?.tab.webView?.loadHTMLString("<html><body>PlayList</body></html>", baseURL: nil)
             self.webLoader = nil
-          })
-            
+          }
+          
           if let timeout = timeout {
-            DispatchQueue.main.asyncAfter(deadline: .now() + LivePlaylistWebLoader.pageLoadTimeout, execute: timeout)
+            Task {
+              _ = try? await timeout.value
+            }
           }
         }
-        return
+        return (nil, nil)
       }
       
       guard let item = PlaylistInfo.from(message: message),
         item.detected
       else {
         cancelRequest()
-        return
+        return (nil, nil)
       }
       
       if item.isInvisible {
         timeout?.cancel()
-        timeout = DispatchWorkItem(block: { [weak self] in
-          guard let self = self else { return }
+        timeout = Task.delayed(bySeconds: LivePlaylistWebLoader.pageLoadTimeout) { @MainActor in
           self.webLoader?.handler?(nil)
           self.webLoader?.tab.webView?.loadHTMLString("<html><body>PlayList</body></html>", baseURL: nil)
           self.webLoader = nil
-        })
+        }
           
         if let timeout = timeout {
-          DispatchQueue.main.asyncAfter(deadline: .now() + LivePlaylistWebLoader.pageLoadTimeout, execute: timeout)
+          Task {
+            _ = try? await timeout.value
+          }
         }
-        return
+        return (nil, nil)
       }
 
       // For now, we ignore base64 video mime-types loaded via the `data:` scheme.
       if item.duration <= 0.0 && !item.detected || item.src.isEmpty || item.src.hasPrefix("data:") || item.src.hasPrefix("blob:") {
         cancelRequest()
-        return
+        return (nil, nil)
       }
         
-      DispatchQueue.main.async {
+      await MainActor.run {
         if !self.playlistItems.contains(item.src) {
           self.playlistItems.insert(item.src)
           
@@ -224,6 +224,8 @@ class LivePlaylistWebLoader: UIView, PlaylistWebLoader {
         self.webLoader?.tab.webView?.loadHTMLString("<html><body>PlayList</body></html>", baseURL: nil)
         self.webLoader = nil
       }
+      
+      return (nil, nil)
     }
   }
 }
diff --git a/Sources/Brave/Frontend/Browser/Playlist/Managers & Cache/PlaylistCarplayManager.swift b/Sources/Brave/Frontend/Browser/Playlist/Managers & Cache/PlaylistCarplayManager.swift
index 54aa844419c..a779720076d 100644
--- a/Sources/Brave/Frontend/Browser/Playlist/Managers & Cache/PlaylistCarplayManager.swift	
+++ b/Sources/Brave/Frontend/Browser/Playlist/Managers & Cache/PlaylistCarplayManager.swift	
@@ -32,6 +32,7 @@ public class PlaylistCarplayManager: NSObject {
   var isPlaylistControllerPresented = false
 
   // When Picture-In-Picture is enabled, we need to store a reference to the controller to keep it alive, otherwise if it deallocates, the system automatically kills Picture-In-Picture.
+  @MainActor
   var playlistController: PlaylistViewController? {
     didSet {
       // TODO: REFACTOR and Decide what happens to Playlist in multiple windows in the future
@@ -54,6 +55,7 @@ public class PlaylistCarplayManager: NSObject {
     }
   }
   
+  @MainActor
   public func destroyPiP() {
     // This is the only way to have the system kill picture in picture as the restoration controller is deallocated
     // And that means the video is deallocated, its AudioSession is stopped, and the Picture-In-Picture controller is deallocated.
@@ -69,6 +71,7 @@ public class PlaylistCarplayManager: NSObject {
   // in use at any given moment
   public static let shared = PlaylistCarplayManager()
 
+  @MainActor
   func getCarPlayController() -> PlaylistCarplayController? {
     // On iOS 14, we use CPTemplate (Custom UI)
     // We control what gets displayed
@@ -106,6 +109,7 @@ public class PlaylistCarplayManager: NSObject {
     return carPlayController
   }
 
+  @MainActor
   func getPlaylistController(tab: Tab?, initialItem: PlaylistInfo?, initialItemPlaybackOffset: Double) -> PlaylistViewController {
 
     // If background playback is enabled (on iPhone), tabs will continue to play media
@@ -132,6 +136,7 @@ public class PlaylistCarplayManager: NSObject {
     return playlistController
   }
 
+  @MainActor
   func getPlaylistController(tab: Tab?, completion: @escaping (PlaylistViewController) -> Void) {
     if let playlistController = self.playlistController {
       return completion(playlistController)
@@ -157,6 +162,7 @@ public class PlaylistCarplayManager: NSObject {
     }
   }
 
+  @MainActor
   private func attemptInterfaceConnection(isCarPlayAvailable: Bool) {
     self.isCarPlayAvailable = isCarPlayAvailable
 
diff --git a/Sources/Brave/Frontend/Browser/Tab.swift b/Sources/Brave/Frontend/Browser/Tab.swift
index 23e0e385035..8a7088e21ed 100644
--- a/Sources/Brave/Frontend/Browser/Tab.swift
+++ b/Sources/Brave/Frontend/Browser/Tab.swift
@@ -30,8 +30,9 @@ protocol TabContentScript: TabContentScriptLoader {
   
   func verifyMessage(message: WKScriptMessage) -> Bool
   func verifyMessage(message: WKScriptMessage, securityToken: String) -> Bool
-  
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: @escaping (Any?, String?) -> Void)
+
+  @MainActor
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?)
 }
 
 protocol TabDelegate {
@@ -75,6 +76,7 @@ enum TabSecureContentState {
   }
 }
 
+@MainActor
 class Tab: NSObject {
   let id: UUID
   let rewardsId: UInt32
@@ -493,27 +495,19 @@ class Tab: NSObject {
     }
     webView = nil
   }
-
-  deinit {
+  
+  func destroy() {
     deleteWebView()
     deleteNewTabPageController()
     contentScriptManager.helpers.removeAll()
-    
-    // A number of mojo-powered core objects have to be deconstructed on the same
-    // thread they were constructed
-    var mojoObjects: [Any?] = [
-      _faviconDriver,
-      _syncTab,
-      _walletEthProvider,
-      _walletSolProvider,
-      _walletKeyringService
-    ]
-    
-    DispatchQueue.main.async {
-      // Reference inside to retain it, supress warnings by reading/writing
-      _ = mojoObjects
-      mojoObjects = []
-    }
+  }
+
+  deinit {
+//    Task { @MainActor in
+//      deleteWebView()
+//      deleteNewTabPageController()
+//      contentScriptManager.helpers.removeAll()
+//    }
   }
 
   var loading: Bool {
@@ -902,23 +896,26 @@ extension Tab: TabWebViewDelegate {
 private class TabContentScriptManager: NSObject, WKScriptMessageHandlerWithReply {
   fileprivate var helpers = [String: TabContentScript]()
 
+  @MainActor
   func uninstall(from tab: Tab) {
     helpers.forEach {
       let name = type(of: $0.value).messageHandlerName
       tab.webView?.configuration.userContentController.removeScriptMessageHandler(forName: name)
     }
   }
-
-  @objc func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage, replyHandler: @escaping (Any?, String?) -> Void) {
+  
+  @MainActor
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     for helper in helpers.values {
       let scriptMessageHandlerName = type(of: helper).messageHandlerName
       if scriptMessageHandlerName == message.name {
-        helper.userContentController(userContentController, didReceiveScriptMessage: message, replyHandler: replyHandler)
-        return
+        return await helper.userContentController(userContentController, didReceive: message)
       }
     }
+    return (nil, nil)
   }
 
+  @MainActor 
   func addContentScript(_ helper: TabContentScript, name: String, forTab tab: Tab, contentWorld: WKContentWorld) {
     if let _ = helpers[name] {
       assertionFailure("Duplicate helper added: \(name)")
@@ -932,6 +929,7 @@ private class TabContentScriptManager: NSObject, WKScriptMessageHandlerWithReply
     tab.webView?.configuration.userContentController.addScriptMessageHandler(self, contentWorld: contentWorld, name: scriptMessageHandlerName)
   }
   
+  @MainActor 
   func removeContentScript(name: String, forTab tab: Tab, contentWorld: WKContentWorld) {
     if let helper = helpers[name] {
       let scriptMessageHandlerName = type(of: helper).messageHandlerName
diff --git a/Sources/Brave/Frontend/Browser/TabManager.swift b/Sources/Brave/Frontend/Browser/TabManager.swift
index df2cd8c781c..d442009140d 100644
--- a/Sources/Brave/Frontend/Browser/TabManager.swift
+++ b/Sources/Brave/Frontend/Browser/TabManager.swift
@@ -45,6 +45,7 @@ class WeakTabManagerDelegate {
 }
 
 // TabManager must extend NSObjectProtocol in order to implement WKNavigationDelegate
+@MainActor
 class TabManager: NSObject {
   fileprivate var delegates = [WeakTabManagerDelegate]()
   fileprivate let tabEventHandlers: [TabEventHandler]
diff --git a/Sources/Brave/Frontend/Browser/TabType.swift b/Sources/Brave/Frontend/Browser/TabType.swift
index de6c6d5bf5a..8d103183994 100644
--- a/Sources/Brave/Frontend/Browser/TabType.swift
+++ b/Sources/Brave/Frontend/Browser/TabType.swift
@@ -36,8 +36,8 @@ enum TabType: Int, CustomDebugStringConvertible {
   ///
   /// - parameter tab: An object representing a Tab.
   /// - returns: A Tab type.
+  @MainActor
   static func of(_ tab: Tab?) -> TabType {
     return tab?.type ?? .regular
   }
-
 }
diff --git a/Sources/Brave/Frontend/Browser/Tabs/TabTray/TabTrayController.swift b/Sources/Brave/Frontend/Browser/Tabs/TabTray/TabTrayController.swift
index de17ff6f165..16e6f997b3d 100644
--- a/Sources/Brave/Frontend/Browser/Tabs/TabTray/TabTrayController.swift
+++ b/Sources/Brave/Frontend/Browser/Tabs/TabTray/TabTrayController.swift
@@ -222,12 +222,12 @@ class TabTrayController: AuthenticationController {
   required init?(coder: NSCoder) { fatalError() }
 
   deinit {
-    tabManager.removeDelegate(self)
-    
-    // Remove the open tabs service observer
-    if let observer = openTabsSessionServiceListener {
-      braveCore.openTabsAPI.removeObserver(observer)
-    }
+//    tabManager.removeDelegate(self)
+//
+//    // Remove the open tabs service observer
+//    if let observer = openTabsSessionServiceListener {
+//      braveCore.openTabsAPI.removeObserver(observer)
+//    }
   }
 
   override func viewDidLoad() {
@@ -332,6 +332,17 @@ class TabTrayController: AuthenticationController {
     }
   }
   
+  override func viewDidDisappear(_ animated: Bool) {
+    super.viewDidDisappear(animated)
+
+    tabManager.removeDelegate(self)
+    
+    // Remove the open tabs service observer
+    if let observer = openTabsSessionServiceListener {
+      braveCore.openTabsAPI.removeObserver(observer)
+    }
+  }
+  
   override func loadView() {
     createTypeSelectorItems()
     layoutTabTray()
diff --git a/Sources/Brave/Frontend/Browser/Toolbars/BottomToolbar/Menu/VPNMenuButton.swift b/Sources/Brave/Frontend/Browser/Toolbars/BottomToolbar/Menu/VPNMenuButton.swift
index 0a6e668ba22..a72f3fdf15a 100644
--- a/Sources/Brave/Frontend/Browser/Toolbars/BottomToolbar/Menu/VPNMenuButton.swift
+++ b/Sources/Brave/Frontend/Browser/Toolbars/BottomToolbar/Menu/VPNMenuButton.swift
@@ -35,6 +35,7 @@ struct VPNMenuButton: View {
   
   @ScaledMetric private var iconSize: CGFloat = 32.0
 
+  @MainActor
   private var isVPNEnabledBinding: Binding<Bool> {
     Binding(
       get: { isVPNEnabled },
@@ -42,6 +43,7 @@ struct VPNMenuButton: View {
     )
   }
 
+  @MainActor
   private func toggleVPN(_ enabled: Bool) {
     if BraveSkusManager.keepShowingSessionExpiredState {
       let alert = BraveSkusManager.sessionExpiredStateAlert(loginCallback: { _ in
@@ -80,6 +82,7 @@ struct VPNMenuButton: View {
     }
   }
 
+  @MainActor
   private var vpnToggle: some View {
     Toggle("Brave VPN", isOn: isVPNEnabledBinding)
       .toggleStyle(SwitchToggleStyle(tint: retryStateActive ? Color(.braveErrorBorder) : .accentColor))
diff --git a/Sources/Brave/Frontend/Browser/UserScriptManager.swift b/Sources/Brave/Frontend/Browser/UserScriptManager.swift
index 3ed659a598c..b838774dca6 100644
--- a/Sources/Brave/Frontend/Browser/UserScriptManager.swift
+++ b/Sources/Brave/Frontend/Browser/UserScriptManager.swift
@@ -12,6 +12,7 @@ import os.log
 
 private class ScriptLoader: TabContentScriptLoader { }
 
+@MainActor
 class UserScriptManager {
   static let shared = UserScriptManager()
   
diff --git a/Sources/Brave/Frontend/Rewards/BraveRewards.swift b/Sources/Brave/Frontend/Rewards/BraveRewards.swift
index b43df547a9e..434b9193af5 100644
--- a/Sources/Brave/Frontend/Rewards/BraveRewards.swift
+++ b/Sources/Brave/Frontend/Rewards/BraveRewards.swift
@@ -176,6 +176,7 @@ public class BraveRewards: NSObject {
   // MARK: - Reporting
 
   /// Report that a tab with a given id was updated
+  @MainActor
   func reportTabUpdated(
     tab: Tab,
     url: URL,
diff --git a/Sources/Brave/Frontend/Share/ShareExtensionHelper.swift b/Sources/Brave/Frontend/Share/ShareExtensionHelper.swift
index 8f7f8938af5..c4e7e65ebb1 100644
--- a/Sources/Brave/Frontend/Share/ShareExtensionHelper.swift
+++ b/Sources/Brave/Frontend/Share/ShareExtensionHelper.swift
@@ -7,6 +7,7 @@ import Shared
 import UIKit
 
 /// A helper class that aids in the creation of share sheets
+@MainActor
 class ShareExtensionHelper {
   /// Create a activity view controller with the given elements.
   /// - Parameters:
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/BlockedDomainScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/BlockedDomainScriptHandler.swift
index 95dcce2d86c..7bca1d752c4 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/BlockedDomainScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/BlockedDomainScriptHandler.swift
@@ -20,17 +20,16 @@ class BlockedDomainScriptHandler: TabContentScript {
   static let scriptSandbox: WKContentWorld = .page
   static let userScript: WKUserScript? = nil
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
-    
+  @MainActor
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message, securityToken: UserScriptManager.securityToken) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
 
     guard let params = message.body as? [String: AnyObject], let action = params["action"] as? String else {
       assertionFailure("Missing required params.")
-      return
+      return (nil, nil)
     }
     
     switch action {
@@ -41,8 +40,11 @@ class BlockedDomainScriptHandler: TabContentScript {
     default:
       assertionFailure("Unhandled action `\(action)`")
     }
+    
+    return (nil, nil)
   }
   
+  @MainActor
   private func blockedDomainDidProceed() {
     guard let url = tab?.url?.stippedInternalURL, let etldP1 = url.baseDomain else {
       assertionFailure("There should be no way this method can be triggered if the tab is not on an internal url")
@@ -54,6 +56,7 @@ class BlockedDomainScriptHandler: TabContentScript {
     tab?.loadRequest(request)
   }
   
+  @MainActor
   private func blockedDomainDidGoBack() {
     guard let url = tab?.url?.stippedInternalURL else {
       assertionFailure("There should be no way this method can be triggered if the tab is not on an internal url")
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/ErrorPageScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/ErrorPageScriptHandler.swift
index 4ae25393bf8..493d7784500 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/ErrorPageScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/ErrorPageScriptHandler.swift
@@ -17,12 +17,10 @@ extension ErrorPageHelper: TabContentScript {
   static let scriptSandbox: WKContentWorld = .page
   static let userScript: WKUserScript? = nil
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
-    
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
     
     guard let errorURL = message.frameInfo.request.url,
@@ -31,21 +29,24 @@ extension ErrorPageHelper: TabContentScript {
       let originalURL = internalUrl.originalURLFromErrorPage,
       let res = message.body as? [String: String],
       let type = res["type"]
-    else { return }
+    else {
+      return (nil, nil)
+    }
 
     switch type {
     case MessageOpenInSafari:
-      UIApplication.shared.open(originalURL, options: [:])
+      await UIApplication.shared.open(originalURL, options: [:])
     case MessageCertVisitOnce:
       if let cert = CertificateErrorPageHandler.certsFromErrorURL(errorURL)?.first,
         let host = originalURL.host {
         let origin = "\(host):\(originalURL.port ?? 443)"
         addCertificate(cert, forOrigin: origin)
-        message.webView?.replaceLocation(with: originalURL)
+        await message.webView?.replaceLocation(with: originalURL)
         // webview.reload will not change the error URL back to the original URL
       }
     default:
       assertionFailure("Unknown error message")
     }
+    return (nil, nil)
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/SessionRestoreScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/SessionRestoreScriptHandler.swift
index f0f8a2d3916..58a0be74dde 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/SessionRestoreScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/SessionRestoreScriptHandler.swift
@@ -34,20 +34,20 @@ class SessionRestoreScriptHandler: TabContentScript {
                         in: scriptSandbox)
   }()
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
-    
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message, securityToken: UserScriptManager.securityToken) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
 
     if let tab = tab, let params = message.body as? [String: AnyObject] {
       if params["name"] as? String == "didRestoreSession" {
-        DispatchQueue.main.async {
+        await MainActor.run {
           self.delegate?.sessionRestore(self, didRestoreSessionForTab: tab)
         }
       }
     }
+    
+    return (nil, nil)
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/Web3IPFSScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/Web3IPFSScriptHandler.swift
index b47fa8023a0..e520afb8d13 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/Web3IPFSScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/Web3IPFSScriptHandler.swift
@@ -27,11 +27,9 @@ class Web3IPFSScriptHandler: TabContentScript {
   static let scriptSandbox: WKContentWorld = .page
   static let userScript: WKUserScript? = nil
   
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
-    
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     guard let params = message.body as? [String: String], let originalURL = originalURL else {
-      return
+      return (nil, nil)
     }
     
     if params["type"] == "IPFSDisable" {
@@ -41,5 +39,7 @@ class Web3IPFSScriptHandler: TabContentScript {
     } else {
       assertionFailure("Invalid message: \(message.body)")
     }
+    
+    return (nil, nil)
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/Web3NameServiceScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/Web3NameServiceScriptHandler.swift
index 0bc53b28538..6dc3407ef25 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/Web3NameServiceScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Internal/Web3NameServiceScriptHandler.swift
@@ -38,11 +38,9 @@ class Web3NameServiceScriptHandler: TabContentScript {
   static let scriptSandbox: WKContentWorld = .page
   static let userScript: WKUserScript? = nil
   
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
-    
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     guard let params = message.body as? [String: String], let originalURL = originalURL else {
-      return
+      return (nil, nil)
     }
     
     if params[ParamKey.buttonType.rawValue] == ParamValue.disable.rawValue,
@@ -56,5 +54,7 @@ class Web3NameServiceScriptHandler: TabContentScript {
     } else {
       assertionFailure("Invalid message: \(message.body)")
     }
+    
+    return (nil, nil)
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/BraveSearchScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/BraveSearchScriptHandler.swift
index 7803e334741..8ebe4d7e012 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/BraveSearchScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/BraveSearchScriptHandler.swift
@@ -58,14 +58,10 @@ class BraveSearchScriptHandler: TabContentScript {
     let methodId: Int
   }
 
-  func userContentController(
-    _ userContentController: WKUserContentController,
-    didReceiveScriptMessage message: WKScriptMessage,
-    replyHandler: (Any?, String?) -> Void
-  ) {
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
     
     let allowedHosts = DomainUserScript.braveSearchHelper.associatedDomains
@@ -75,40 +71,37 @@ class BraveSearchScriptHandler: TabContentScript {
       message.frameInfo.isMainFrame
     else {
       Logger.module.error("Backup search request called from disallowed host")
-      replyHandler(nil, nil)
-      return
+      return (nil, nil)
     }
 
     guard let data = try? JSONSerialization.data(withJSONObject: message.body, options: []),
       let method = try? JSONDecoder().decode(MethodModel.self, from: data).methodId
     else {
       Logger.module.error("Failed to retrieve method id")
-      replyHandler(nil, nil)
-      return
+      return (nil, nil)
     }
 
     switch method {
     case Method.canSetBraveSearchAsDefault.rawValue:
-      handleCanSetBraveSearchAsDefault(replyHandler: replyHandler)
+      return await handleCanSetBraveSearchAsDefault()
     case Method.setBraveSearchDefault.rawValue:
-      handleSetBraveSearchDefault(replyHandler: replyHandler)
+      return await handleSetBraveSearchDefault()
     default:
-      break
+      return (nil, nil)
     }
   }
 
-  private func handleCanSetBraveSearchAsDefault(replyHandler: (Any?, String?) -> Void) {
+  @MainActor
+  private func handleCanSetBraveSearchAsDefault() async -> (Any?, String?) {
     if tab?.isPrivate == true {
       Logger.module.debug("Private mode detected, skipping setting Brave Search as a default")
-      replyHandler(false, nil)
-      return
+      return (false, nil)
     }
 
     let maximumPromptCount = Preferences.Search.braveSearchDefaultBrowserPromptCount
     if Self.canSetAsDefaultCounter >= maxCountOfDefaultBrowserPromptsPerSession || maximumPromptCount.value >= maxCountOfDefaultBrowserPromptsTotal {
       Logger.module.debug("Maximum number of tries of Brave Search website prompts reached")
-      replyHandler(false, nil)
-      return
+      return (false, nil)
     }
 
     Self.canSetAsDefaultCounter += 1
@@ -116,11 +109,11 @@ class BraveSearchScriptHandler: TabContentScript {
 
     let defaultEngine = profile.searchEngines.defaultEngine(forType: .standard).shortName
     let canSetAsDefault = defaultEngine != OpenSearchEngine.EngineNames.brave
-    replyHandler(canSetAsDefault, nil)
+    return (canSetAsDefault, nil)
   }
 
-  private func handleSetBraveSearchDefault(replyHandler: (Any?, String?) -> Void) {
+  private func handleSetBraveSearchDefault() async -> (Any?, String?) {
     profile.searchEngines.updateDefaultEngine(OpenSearchEngine.EngineNames.brave, forType: .standard)
-    replyHandler(nil, nil)
+    return (nil, nil)
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/BraveSkusScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/BraveSkusScriptHandler.swift
index 6d14930d6a0..01019704c0b 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/BraveSkusScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/BraveSkusScriptHandler.swift
@@ -16,6 +16,7 @@ class BraveSkusScriptHandler: TabContentScript {
   
   private let braveSkusManager: BraveSkusManager
   
+  @MainActor
   required init?(tab: Tab) {
     guard let manager = BraveSkusManager(isPrivateMode: tab.isPrivate) else {
       return nil
@@ -47,12 +48,10 @@ class BraveSkusScriptHandler: TabContentScript {
     case credentialsSummary = 4
   }
   
-  func userContentController(_ userContentController: WKUserContentController,
-                             didReceiveScriptMessage message: WKScriptMessage,
-                             replyHandler: @escaping (Any?, String?) -> Void) {
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
     
     let allowedHosts = DomainUserScript.braveSkus.associatedDomains
@@ -61,40 +60,38 @@ class BraveSkusScriptHandler: TabContentScript {
           allowedHosts.contains(requestHost),
           message.frameInfo.isMainFrame else {
       Logger.module.error("Brave skus request called from disallowed host")
-      return
+      return (nil, nil)
     }
     
     guard let response = message.body as? [String: Any],
           let methodId = response["method_id"] as? Int,
           let data = response["data"] as? [String: Any] else {
       Logger.module.error("Failed to retrieve method id")
-      return
+      return (nil, nil)
     }
     
     switch methodId {
     case Method.refreshOrder.rawValue:
       if let orderId = data["orderId"] as? String {
         
-        braveSkusManager.refreshOrder(for: orderId, domain: requestHost) { result in
-          replyHandler(result, nil)
-        }
+        let result = await braveSkusManager.refreshOrder(for: orderId, domain: requestHost)
+        return (result, nil)
       }
     case Method.fetchOrderCredentials.rawValue:
       if let orderId = data["orderId"] as? String {
-        braveSkusManager.fetchOrderCredentials(for: orderId, domain: requestHost) { result in
-          replyHandler(result, nil)
-        }
+        let result = await braveSkusManager.fetchOrderCredentials(for: orderId, domain: requestHost)
+        return (result, nil)
       }
     case Method.prepareCredentialsPresentation.rawValue:
       assertionFailure("The website should never call the credentialsPresentation.")
     case Method.credentialsSummary.rawValue:
       if let domain = data["domain"] as? String {
-        braveSkusManager.credentialSummary(for: domain) { result in
-          replyHandler(result, nil)
-        }
+        let result = await braveSkusManager.credentialSummary(for: domain)
+        return (result, nil)
       }
     default:
       assertionFailure("Failure, the website called unhandled method with id: \(methodId)")
     }
+    return (nil, nil)
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/BraveTalkScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/BraveTalkScriptHandler.swift
index faa37a3a60e..8d764a3bce8 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/BraveTalkScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/BraveTalkScriptHandler.swift
@@ -19,6 +19,7 @@ class BraveTalkScriptHandler: TabContentScript {
   private var rewardsEnabledReplyHandler: ((Any?, String?) -> Void)?
   private let launchNativeBraveTalk: (_ tab: Tab?, _ room: String, _ token: String) -> Void
 
+  @MainActor
   required init(
     tab: Tab,
     rewards: BraveRewards,
@@ -81,14 +82,10 @@ class BraveTalkScriptHandler: TabContentScript {
     }
   }
   
-  func userContentController(
-    _ userContentController: WKUserContentController,
-    didReceiveScriptMessage message: WKScriptMessage,
-    replyHandler: @escaping (Any?, String?) -> Void
-  ) {
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
     
     let allowedHosts = DomainUserScript.braveTalkHelper.associatedDomains
@@ -98,46 +95,51 @@ class BraveTalkScriptHandler: TabContentScript {
       message.frameInfo.isMainFrame
     else {
       Logger.module.error("Backup search request called from disallowed host")
-      replyHandler(nil, nil)
-      return
+      return (nil, nil)
     }
     
     guard let json = try? JSONSerialization.data(withJSONObject: message.body, options: []),
           let payload = try? JSONDecoder().decode(Payload.self, from: json) else {
-      return
+      return (nil, nil)
     }
 
     switch payload.kind {
     case .braveRequestAdsEnabled:
-      handleBraveRequestAdsEnabled(replyHandler)
+      return await withCheckedContinuation { continuation in
+        handleBraveRequestAdsEnabled { result, error in
+          continuation.resume(returning: (result, error))
+        }
+      }
     case .launchNativeBraveTalk(let url):
       guard let components = URLComponents(string: url),
             case let room = String(components.path.dropFirst(1)),
             let jwt = components.queryItems?.first(where: { $0.name == "jwt" })?.value
       else {
-        return
+        return (nil, nil)
       }
       launchNativeBraveTalk(tab, room, jwt)
-      replyHandler(nil, nil)
+      return (nil, nil)
     }
   }
 
   private func handleBraveRequestAdsEnabled(_ replyHandler: @escaping (Any?, String?) -> Void) {
-    guard let rewards = rewards, tab?.isPrivate != true else {
-      replyHandler(false, nil)
-      return
-    }
-
-    if rewards.isEnabled {
-      replyHandler(true, nil)
-      return
-    }
-
-    // If rewards are disabled we show a Rewards panel,
-    // The `rewardsEnabledReplyHandler` will be called from other place.
-    if let tab = tab {
-      rewardsEnabledReplyHandler = replyHandler
-      tab.tabDelegate?.showRequestRewardsPanel(tab)
+    Task { @MainActor in
+      guard let rewards = rewards, tab?.isPrivate != true else {
+        replyHandler(false, nil)
+        return
+      }
+      
+      if rewards.isEnabled {
+        replyHandler(true, nil)
+        return
+      }
+      
+      // If rewards are disabled we show a Rewards panel,
+      // The `rewardsEnabledReplyHandler` will be called from other place.
+      if let tab = tab {
+        rewardsEnabledReplyHandler = replyHandler
+        tab.tabDelegate?.showRequestRewardsPanel(tab)
+      }
     }
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/ContentBlockerScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/ContentBlockerScriptHandler.swift
index 0782a967096..d436c0d7cf2 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/ContentBlockerScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/ContentBlockerScriptHandler.swift
@@ -47,17 +47,15 @@ extension ContentBlockerHelper: TabContentScript {
     blockedRequests.removeAll()
   }
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
-    
-    guard let currentTabURL = tab?.webView?.url else {
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
+    guard let currentTabURL = await tab?.webView?.url else {
       assertionFailure("Missing tab or webView")
-      return
+      return (nil, nil)
     }
     
     if !verifyMessage(message: message, securityToken: UserScriptManager.securityToken) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
     
     do {
@@ -134,5 +132,7 @@ extension ContentBlockerHelper: TabContentScript {
     } catch {
       Logger.module.error("\(error.localizedDescription)")
     }
+    
+    return (nil, nil)
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/CosmeticFiltersScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/CosmeticFiltersScriptHandler.swift
index ac5c74e5ebd..d9c21c8c28b 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/CosmeticFiltersScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/CosmeticFiltersScriptHandler.swift
@@ -36,11 +36,10 @@ class CosmeticFiltersScriptHandler: TabContentScript {
     self.tab = tab
   }
   
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: @escaping (Any?, String?) -> Void) {
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message) {
       assertionFailure("Invalid security token. Fix the `RequestBlocking.js` script")
-      replyHandler(nil, nil)
-      return
+      return (nil, nil)
     }
 
     do {
@@ -48,11 +47,10 @@ class CosmeticFiltersScriptHandler: TabContentScript {
       let dto = try JSONDecoder().decode(CosmeticFiltersDTO.self, from: data)
       
       guard let frameURL = URL(string: dto.data.sourceURL) else {
-        replyHandler(nil, nil)
-        return
+        return (nil, nil)
       }
       
-      Task { @MainActor in
+      return await Task { @MainActor in
         let domain = Domain.getOrCreate(forUrl: frameURL, persistent: self.tab?.isPrivate == true ? false : true)
         let cachedEngines = await AdBlockStats.shared.cachedEngines(for: domain)
         
@@ -83,14 +81,14 @@ class CosmeticFiltersScriptHandler: TabContentScript {
           }
         }
         
-        replyHandler([
+        return ([
           "aggressiveSelectors": Array(aggressiveSelectors),
           "standardSelectors": Array(standardSelectors)
         ], nil)
-      }
+      }.value
     } catch {
       assertionFailure("Invalid type of message. Fix the `RequestBlocking.js` script")
-      replyHandler(nil, nil)
+      return (nil, nil)
     }
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/EthereumProviderScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/EthereumProviderScriptHandler.swift
index 71979f4a24e..25f5d9ec693 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/EthereumProviderScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/EthereumProviderScriptHandler.swift
@@ -60,14 +60,11 @@ class EthereumProviderScriptHandler: TabContentScript {
     }
   }
   
-  @MainActor func userContentController(
-    _ userContentController: WKUserContentController,
-    didReceiveScriptMessage message: WKScriptMessage,
-    replyHandler: @escaping (Any?, String?) -> Void
-  ) {
+  @MainActor 
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
     
     guard let tab = tab,
@@ -80,55 +77,53 @@ class EthereumProviderScriptHandler: TabContentScript {
           let body = try? JSONDecoder().decode(MessageBody.self, from: messageData)
     else {
       Logger.module.error("Failed to handle ethereum provider communication")
-      return
+      return (nil, nil)
     }
     
     if message.webView?.url?.isLocal == false,
         message.webView?.hasOnlySecureContent == false { // prevent communication in mixed-content scenarios
       Logger.module.error("Failed ethereum provider communication security test")
-      return
+      return (nil, nil)
     }
     
     // The web page has communicated with `window.ethereum`, so we should show the wallet icon
     tab.isWalletIconVisible = true
     
+    @MainActor
     func handleResponse(
-      id: MojoBase.Value,
+      _ response: (id: MojoBase.Value,
       formedResponse: MojoBase.Value,
       reject: Bool,
       firstAllowedAccount: String,
-      updateJSProperties: Bool
-    ) {
-      Task { @MainActor in
-        if updateJSProperties {
-          await tab.updateEthereumProperties()
-        }
-        
-        if reject {
-          replyHandler(nil, formedResponse.jsonString)
-        } else {
-          replyHandler(formedResponse.jsonObject, nil)
-        }
+      updateJSProperties: Bool)
+    ) async -> (Any?, String?) {
+      if response.updateJSProperties {
+        await tab.updateEthereumProperties()
+      }
+      
+      if response.reject {
+        return (nil, response.formedResponse.jsonString)
+      } else {
+        return (response.formedResponse.jsonObject, nil)
       }
     }
     
     switch body.method {
     case .request:
       guard let requestPayload = MojoBase.Value(jsonString: body.args) else {
-        replyHandler(nil, "Invalid args")
-        return
+        return (nil, "Invalid args")
       }
-      provider.request(requestPayload, completion: handleResponse)
+      
+      return await handleResponse(provider.request(requestPayload))
     case .isConnected:
-      replyHandler(nil, nil)
+      return (nil, nil)
     case .enable:
-      provider.enable(handleResponse)
+      return await handleResponse(provider.enable())
     case .sendAsync:
       guard let requestPayload = MojoBase.Value(jsonString: body.args) else {
-        replyHandler(nil, "Invalid args")
-        return
+        return (nil, "Invalid args")
       }
-      provider.sendAsync(requestPayload, completion: handleResponse)
+      return await handleResponse(provider.sendAsync(requestPayload))
     case .send:
       struct SendPayload {
         var method: String
@@ -142,37 +137,28 @@ class EthereumProviderScriptHandler: TabContentScript {
         }
       }
       guard let sendPayload = SendPayload(payload: body.args) else {
-        replyHandler(nil, "Invalid args")
-        return
+        return (nil, "Invalid args")
       }
       
       if sendPayload.method.isEmpty {
         if let params = sendPayload.params, params.tag != .null {
-          provider.sendAsync(params, completion: handleResponse)
-        } else {
-          // Empty method with no params is not valid
-          replyHandler(nil, "Invalid args")
+          return await handleResponse(provider.sendAsync(params))
         }
-        return
+        
+        // Empty method with no params is not valid
+        return (nil, "Invalid args")
       }
       
       if !Self.supportedSingleArgMethods.contains(sendPayload.method),
          (sendPayload.params == nil || sendPayload.params?.tag == .null) {
         // If its not a single arg supported method and there are no parameters then its not a valid
         // call
-        replyHandler(nil, "Invalid args")
-        return
+        return (nil, "Invalid args")
       }
       
-      provider.send(
-        sendPayload.method,
-        params: sendPayload.params ?? .init(listValue: []),
-        completion: handleResponse
-      )
+      return await handleResponse(provider.send(sendPayload.method, params: sendPayload.params ?? .init(listValue: [])))
     case .isUnlocked:
-      provider.isLocked { isLocked in
-        replyHandler(!isLocked, nil)
-      }
+      return await (!provider.isLocked(), nil)
     }
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/PlaylistFolderSharingScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/PlaylistFolderSharingScriptHandler.swift
index 0613745d2c0..9994c3b4e9e 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/PlaylistFolderSharingScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/PlaylistFolderSharingScriptHandler.swift
@@ -39,12 +39,10 @@ class PlaylistFolderSharingScriptHandler: NSObject, TabContentScript {
                         in: scriptSandbox)
   }()
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
-
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
     
     if let sharingInfo = PlaylistFolderSharingInfo.from(message: message) {
@@ -56,6 +54,7 @@ class PlaylistFolderSharingScriptHandler: NSObject, TabContentScript {
       
       delegate?.openPlaylistSharingFolder(with: sharedFolderPageUrl)
     }
+    return (nil, nil)
   }
 }
 
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/PlaylistScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/PlaylistScriptHandler.swift
index fdc05c24aa0..11b2659dd3c 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/PlaylistScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/PlaylistScriptHandler.swift
@@ -34,6 +34,7 @@ class PlaylistScriptHandler: NSObject, TabContentScript {
   private var asset: AVURLAsset?
   private static let queue = DispatchQueue(label: "com.playlisthelper.queue", qos: .userInitiated)
 
+  @MainActor
   init(tab: Tab) {
     self.tab = tab
     self.url = tab.url
@@ -90,38 +91,39 @@ class PlaylistScriptHandler: NSObject, TabContentScript {
                         in: scriptSandbox)
   }()
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
-    
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
     
     // If this URL is blocked from Playlist support, do nothing
     if url?.isPlaylistBlockedSiteURL == true {
-      return
+      return (nil, nil)
     }
     
     if ReadyState.from(message: message) != nil {
-      return
+      return (nil, nil)
     }
     
-    Self.processPlaylistInfo(
+    await Self.processPlaylistInfo(
       handler: self,
       item: PlaylistInfo.from(message: message))
+    
+    return (nil, nil)
   }
 
-  private class func processPlaylistInfo(handler: PlaylistScriptHandler, item: PlaylistInfo?) {
+  @MainActor
+  private class func processPlaylistInfo(handler: PlaylistScriptHandler, item: PlaylistInfo?) async {
     guard var item = item, !item.src.isEmpty else {
-      DispatchQueue.main.async {
+      await MainActor.run {
         handler.delegate?.updatePlaylistURLBar(tab: handler.tab, state: .none, item: nil)
       }
       return
     }
     
     if handler.url?.baseDomain != "soundcloud.com", item.isInvisible {
-      DispatchQueue.main.async {
+      await MainActor.run {
         handler.delegate?.updatePlaylistURLBar(tab: handler.tab, state: .none, item: nil)
       }
       return
@@ -213,6 +215,7 @@ class PlaylistScriptHandler: NSObject, TabContentScript {
 
 extension PlaylistScriptHandler: UIGestureRecognizerDelegate {
   @objc
+  @MainActor
   func onLongPressedWebView(_ gestureRecognizer: UILongPressGestureRecognizer) {
     if gestureRecognizer.state == .began,
       let webView = tab?.webView,
@@ -275,6 +278,7 @@ extension PlaylistScriptHandler {
     }
   }
 
+  @MainActor
   static func stopPlayback(tab: Tab?) {
     guard let tab = tab else { return }
 
@@ -290,9 +294,10 @@ extension PlaylistScriptHandler {
 }
 
 extension PlaylistScriptHandler {
-  static func updatePlaylistTab(tab: Tab, item: PlaylistInfo?) {
+  @MainActor
+  static func updatePlaylistTab(tab: Tab, item: PlaylistInfo?) async {
     if let handler = tab.getContentScript(name: Self.scriptName) as? PlaylistScriptHandler {
-      Self.processPlaylistInfo(handler: handler, item: item)
+      await Self.processPlaylistInfo(handler: handler, item: item)
     }
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/PrintScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/PrintScriptHandler.swift
index 855a8e79c90..147f16131ad 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/PrintScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/PrintScriptHandler.swift
@@ -36,12 +36,11 @@ class PrintScriptHandler: TabContentScript {
                         in: scriptSandbox)
   }()
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
-
+  @MainActor
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message, securityToken: UserScriptManager.securityToken) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
 
     if let tab = tab, let webView = tab.webView, let url = webView.url {
@@ -54,7 +53,7 @@ class PrintScriptHandler: TabContentScript {
       currentDomain = url.baseDomain
 
       if isPresentingController || isBlocking {
-        return
+        return (nil, nil)
       }
 
       let showPrintSheet = { [weak self] in
@@ -105,5 +104,7 @@ class PrintScriptHandler: TabContentScript {
         showPrintSheet()
       }
     }
+    
+    return (nil, nil)
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/ReadyStateScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/ReadyStateScriptHandler.swift
index 8360fa8af0a..92e6a171526 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/ReadyStateScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/ReadyStateScriptHandler.swift
@@ -68,20 +68,19 @@ class ReadyStateScriptHandler: TabContentScript {
                         in: scriptSandbox)
   }()
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    
-    defer { replyHandler(nil, nil) }
-    
+  @MainActor
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
 
     guard let readyState = ReadyState.from(message: message) else {
       Logger.module.error("Invalid Ready State")
-      return
+      return (nil, nil)
     }
     
     tab?.onPageReadyStateChanged?(readyState.state)
+    return  (nil, nil)
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/RequestBlockingContentScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/RequestBlockingContentScriptHandler.swift
index d5fac2ab186..eeed899252d 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/RequestBlockingContentScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/RequestBlockingContentScriptHandler.swift
@@ -46,16 +46,16 @@ class RequestBlockingContentScriptHandler: TabContentScript {
     self.tab = tab
   }
   
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: @escaping (Any?, String?) -> Void) {
+  @MainActor
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     guard let tab = tab, let currentTabURL = tab.webView?.url else {
       assertionFailure("Should have a tab set")
-      return
+      return (nil, nil)
     }
     
     if !verifyMessage(message: message) {
       assertionFailure("Invalid security token. Fix the `RequestBlocking.js` script")
-      replyHandler(false, nil)
-      return
+      return (false, nil)
     }
 
     do {
@@ -64,13 +64,13 @@ class RequestBlockingContentScriptHandler: TabContentScript {
       
       // Because javascript urls allow some characters that `URL` does not,
       // we use `NSURL(idnString: String)` to parse them
-      guard let requestURL = NSURL(idnString: dto.data.resourceURL) as URL? else { return }
-      guard let sourceURL = NSURL(idnString: dto.data.sourceURL) as URL? else { return }
+      guard let requestURL = NSURL(idnString: dto.data.resourceURL) as URL? else { return (nil, nil) }
+      guard let sourceURL = NSURL(idnString: dto.data.sourceURL) as URL? else { return (nil, nil) }
       let isPrivateBrowsing = tab.isPrivate
       
-      Task { @MainActor in
+      return await Task { @MainActor in
         let domain = Domain.getOrCreate(forUrl: currentTabURL, persistent: !isPrivateBrowsing)
-        guard let domainURLString = domain.url else { return }
+        guard let domainURLString = domain.url else { return (nil, nil) }
         let shouldBlock = await AdBlockStats.shared.shouldBlock(
           requestURL: requestURL, sourceURL: sourceURL, resourceType: dto.data.resourceType,
           isAggressiveMode: domain.blockAdsAndTrackingLevel.isAggressive
@@ -82,9 +82,8 @@ class RequestBlockingContentScriptHandler: TabContentScript {
         // For subframes which may use different etld+1 than the main frame (example `reddit.com` and `redditmedia.com`)
         // We simply check the known subframeURLs on this page.
         guard tab.url?.baseDomain == sourceURL.baseDomain ||
-              self.tab?.currentPageData?.allSubframeURLs.contains(sourceURL) == true else {
-          replyHandler(shouldBlock, nil)
-          return
+                self.tab?.currentPageData?.allSubframeURLs.contains(sourceURL) == true else {
+          return (shouldBlock, nil)
         }
         
         if shouldBlock, Preferences.PrivacyReports.captureShieldsData.value,
@@ -93,7 +92,7 @@ class RequestBlockingContentScriptHandler: TabContentScript {
            !isPrivateBrowsing {
           PrivacyReportsManager.pendingBlockedRequests.append((blockedResourceHost, domainURL, Date()))
         }
-
+        
         if shouldBlock && !tab.contentBlocker.blockedRequests.contains(requestURL) {
           BraveGlobalShieldStats.shared.adblock += 1
           let stats = tab.contentBlocker.stats
@@ -101,11 +100,11 @@ class RequestBlockingContentScriptHandler: TabContentScript {
           tab.contentBlocker.blockedRequests.insert(requestURL)
         }
         
-        replyHandler(shouldBlock, nil)
-      }
+        return (shouldBlock, nil)
+      }.value
     } catch {
       assertionFailure("Invalid type of message. Fix the `RequestBlocking.js` script")
-      replyHandler(false, nil)
+      return (false, nil)
     }
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/RewardsReportingScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/RewardsReportingScriptHandler.swift
index acdd7f3dba3..5dcaa48847f 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/RewardsReportingScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/RewardsReportingScriptHandler.swift
@@ -34,45 +34,48 @@ class RewardsReportingScriptHandler: TabContentScript {
                         in: scriptSandbox)
   }()
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     struct Content: Decodable {
       var method: String
       var url: String
       var data: String?
       var referrerUrl: String?
     }
-
-    if tab?.isPrivate == true || !rewards.isEnabled {
-      return
-    }
     
     if !verifyMessage(message: message) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
-
-    do {
+    
+    await MainActor.run {
+      guard let tab = tab, !tab.isPrivate, rewards.isEnabled, let tabURL = tab.url else {
+        return
+      }
+      
       guard let body = message.body as? [String: AnyObject] else {
         return
       }
-
-      if let body = body["data"] as? [String: AnyObject] {
-        let json = try JSONSerialization.data(withJSONObject: body, options: [])
-        var content = try JSONDecoder().decode(Content.self, from: json)
-
-        guard let tab = tab, let tabURL = tab.url else { return }
-
-        if content.url.hasPrefix("//") {
-          content.url = "\(tabURL.scheme ?? "http"):\(content.url)"
+      
+      Task {
+        do {
+          if let body = body["data"] as? [String: AnyObject] {
+            let json = try JSONSerialization.data(withJSONObject: body, options: [])
+            var content = try JSONDecoder().decode(Content.self, from: json)
+            
+            if content.url.hasPrefix("//") {
+              content.url = "\(tabURL.scheme ?? "http"):\(content.url)"
+            }
+            
+            guard let url = URL(string: content.url) else { return }
+            let refURL = URL(string: content.referrerUrl ?? "")
+            rewards.reportXHRLoad(url: url, tabId: Int(tab.rewardsId), firstPartyURL: tabURL, referrerURL: refURL)
+          }
+        } catch {
+          adsRewardsLog.error("Failed to parse message from rewards reporting JS: \(error.localizedDescription)")
         }
-
-        guard let url = URL(string: content.url) else { return }
-        let refURL = URL(string: content.referrerUrl ?? "")
-        rewards.reportXHRLoad(url: url, tabId: Int(tab.rewardsId), firstPartyURL: tabURL, referrerURL: refURL)
       }
-    } catch {
-      adsRewardsLog.error("Failed to parse message from rewards reporting JS: \(error.localizedDescription)")
     }
+    
+    return (nil, nil)
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/SolanaProviderScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/SolanaProviderScriptHandler.swift
index 8bf664b7501..9d8c1bac832 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/SolanaProviderScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/SolanaProviderScriptHandler.swift
@@ -71,10 +71,11 @@ class SolanaProviderScriptHandler: TabContentScript {
     }
   }
   
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: @escaping (Any?, String?) -> Void) {
+  @MainActor
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
     
     guard let tab = tab,
@@ -87,57 +88,56 @@ class SolanaProviderScriptHandler: TabContentScript {
           let body = try? JSONDecoder().decode(MessageBody.self, from: messageData)
     else {
       Logger.module.error("Failed to handle solana provider communication")
-      return
+      return (nil, nil)
     }
     
     if message.webView?.url?.isLocal == false,
        message.webView?.hasOnlySecureContent == false { // prevent communication in mixed-content scenarios
       Logger.module.error("Failed solana provider communication security test")
-      return
+      return (nil, nil)
     }
     
     // The web page has communicated with `window.solana`, so we should show the wallet icon
     tab.isWalletIconVisible = true
     
-    Task { @MainActor in
+    return await Task { @MainActor in
       switch body.method {
       case .connect:
         let (publicKey, error) = await connect(args: body.args)
-        replyHandler(publicKey, error)
         if let publicKey = publicKey as? String {
           await emitConnectEvent(publicKey: publicKey)
         }
+        return (publicKey, error)
       case .disconnect:
         provider.disconnect()
-        replyHandler("{:}", nil)
+        return ("{:}", nil)
       case .signAndSendTransaction:
         let (result, error) = await signAndSendTransaction(args: body.args)
-        replyHandler(result, error)
+        return (result, error)
       case .signMessage:
         let (result, error) = await signMessage(args: body.args)
-        replyHandler(result, error)
+        return (result, error)
       case .request:
         guard let args = body.args,
               let argDict = MojoBase.Value(jsonString: args)?.dictionaryValue,
               let method = argDict[Keys.method.rawValue]?.stringValue else {
-          replyHandler(nil, buildErrorJson(status: .invalidParams, errorMessage: "Invalid args"))
-          return
+          return (nil, buildErrorJson(status: .invalidParams, errorMessage: "Invalid args"))
         }
         let (result, error) = await request(args: body.args)
-        replyHandler(result, error)
         if method == Keys.connect.rawValue, let publicKey = result as? String {
           await emitConnectEvent(publicKey: publicKey)
         } else if method == Keys.disconnect.rawValue {
           tab.emitSolanaEvent(.disconnect)
         }
+        return (result, error)
       case .signTransaction:
         let (result, error) = await signTransaction(args: body.args)
-        replyHandler(result, error)
+        return (result, error)
       case .signAllTransactions:
         let (result, error) = await signAllTransactions(args: body.args)
-        replyHandler(result, error)
+        return (result, error)
       }
-    }
+    }.value
   }
   
   /// Given optional args `{onlyIfTrusted: Bool}`, will return the base 58 encoded public key for success or the error dictionary for failures.
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/URLPartinessScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/URLPartinessScriptHandler.swift
index f4d84d22043..2b9294a9046 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/URLPartinessScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/URLPartinessScriptHandler.swift
@@ -35,11 +35,10 @@ class URLPartinessScriptHandler: TabContentScript {
     self.tab = tab
   }
   
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: @escaping (Any?, String?) -> Void) {
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message) {
       assertionFailure("Invalid security token. Fix the `SelectorsPollerScript.js` script")
-      replyHandler(nil, nil)
-      return
+      return (nil, nil)
     }
 
     do {
@@ -54,8 +53,7 @@ class URLPartinessScriptHandler: TabContentScript {
           results[urlString] = false
         }
         
-        replyHandler(results, nil)
-        return
+        return (results, nil)
       }
       
       let frameETLD1 = frameURL.baseDomain
@@ -71,10 +69,10 @@ class URLPartinessScriptHandler: TabContentScript {
         results[urlString] = frameETLD1 == etld1
       }
       
-      replyHandler(results, nil)
+      return (results, nil)
     } catch {
       assertionFailure("Invalid type of message. Fix the `RequestBlocking.js` script")
-      replyHandler(nil, nil)
+      return (nil, nil)
     }
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/YoutubeQualityScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/YoutubeQualityScriptHandler.swift
index 2f95cdad199..a40b613eaa8 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/YoutubeQualityScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Paged/YoutubeQualityScriptHandler.swift
@@ -14,6 +14,7 @@ class YoutubeQualityScriptHandler: NSObject, TabContentScript {
   private var url: URL?
   private var urlObserver: NSObjectProtocol?
   
+  @MainActor
   init(tab: Tab) {
     self.tab = tab
     self.url = tab.url
@@ -21,12 +22,12 @@ class YoutubeQualityScriptHandler: NSObject, TabContentScript {
     
     urlObserver = tab.webView?.observe(
       \.url, options: [.new],
-       changeHandler: { [weak self] object, change in
+       changeHandler: { [weak self] webView, change in
          guard let self = self, let url = change.newValue else { return }
          if self.url?.withoutFragment != url?.withoutFragment {
            self.url = url
            
-           object.evaluateSafeJavaScript(functionName: "window.__firefox__.\(Self.refreshQuality)",
+           webView.evaluateSafeJavaScript(functionName: "window.__firefox__.\(Self.refreshQuality)",
                                          contentWorld: Self.scriptSandbox,
                                          asFunction: true)
          }
@@ -56,19 +57,20 @@ class YoutubeQualityScriptHandler: NSObject, TabContentScript {
                         in: scriptSandbox)
   }()
   
+  @MainActor
   static func setEnabled(option: Preferences.Option<String>, for tab: Tab) {
     let enabled = canEnableHighQuality(option: option)
     
     tab.webView?.evaluateSafeJavaScript(functionName: "window.__firefox__.\(Self.setQuality)", args: [enabled ? Self.highestQuality: "''"], contentWorld: Self.scriptSandbox, escapeArgs: false, asFunction: true)
   }
   
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
     
-    replyHandler(Self.canEnableHighQuality(option: Preferences.General.youtubeHighQuality) ?
+    return (Self.canEnableHighQuality(option: Preferences.General.youtubeHighQuality) ?
                  Self.highestQuality : "", nil)
   }
   
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/AdsMediaReportingScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/AdsMediaReportingScriptHandler.swift
index 8a7b0f7a89f..2896377a610 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/AdsMediaReportingScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/AdsMediaReportingScriptHandler.swift
@@ -23,25 +23,27 @@ class AdsMediaReportingScriptHandler: TabContentScript {
   static let scriptSandbox: WKContentWorld = .defaultClient
   static let userScript: WKUserScript? = nil
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
-    
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message, securityToken: UserScriptManager.securityToken) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
     
     guard let body = message.body as? [String: AnyObject] else {
-      return
+      return (nil, nil)
     }
 
-    if let isPlaying = body["data"] as? Bool, rewards.isEnabled {
+    await MainActor.run {
       guard let tab = tab else { return }
-      if isPlaying {
-        rewards.reportMediaStarted(tabId: Int(tab.rewardsId))
-      } else {
-        rewards.reportMediaStopped(tabId: Int(tab.rewardsId))
+      
+      if let isPlaying = body["data"] as? Bool, rewards.isEnabled {
+        if isPlaying {
+          rewards.reportMediaStarted(tabId: Int(tab.rewardsId))
+        } else {
+          rewards.reportMediaStopped(tabId: Int(tab.rewardsId))
+        }
       }
     }
+    return (nil, nil)
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/CustomSearchScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/CustomSearchScriptHandler.swift
index e325ac0cc98..5a46d655168 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/CustomSearchScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/CustomSearchScriptHandler.swift
@@ -28,8 +28,8 @@ class CustomSearchScriptHandler: TabContentScript {
                         in: scriptSandbox)
   }()
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    replyHandler(nil, nil)
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     // We don't listen to messages because the BVC calls the searchHelper script by itself.
+    return (nil, nil)
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/DeAmpScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/DeAmpScriptHandler.swift
index 37d5d84cd8d..11b3775eef8 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/DeAmpScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/DeAmpScriptHandler.swift
@@ -35,11 +35,10 @@ public class DeAmpScriptHandler: TabContentScript {
                         in: scriptSandbox)
   }()
   
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: @escaping (Any?, String?) -> Void) {
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message) {
       assertionFailure("Missing required security token.")
-      replyHandler(false, nil)
-      return
+      return (nil, nil)
     }
     
     do {
@@ -50,11 +49,13 @@ public class DeAmpScriptHandler: TabContentScript {
       // or that previousURL is nil which indicates circular loop cause by a client side redirect
       // Also check that our window url does not match the previously committed url
       // or that previousURL is nil which indicates as circular loop caused by a server side redirect
-      let shouldRedirect = dto.destURL != tab?.previousComittedURL && tab?.committedURL != tab?.previousComittedURL
-      replyHandler(shouldRedirect, nil)
+      return await MainActor.run {
+        let shouldRedirect = dto.destURL != tab?.previousComittedURL && tab?.committedURL != tab?.previousComittedURL
+        return (shouldRedirect, nil)
+      }
     } catch {
       assertionFailure("Invalid type of message. Fix the `RequestBlocking.js` script")
-      replyHandler(false, nil)
+      return (false, nil)
     }
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/DownloadContentScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/DownloadContentScriptHandler.swift
index 422f23519dd..fd49439426c 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/DownloadContentScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/DownloadContentScriptHandler.swift
@@ -33,6 +33,7 @@ class DownloadContentScriptHandler: TabContentScript {
   static let scriptSandbox: WKContentWorld = .defaultClient
   static let userScript: WKUserScript? = nil
   
+  @MainActor
   static func downloadBlob(url: URL, tab: Tab) -> Bool {
     let safeUrl = url.absoluteString.replacingOccurrences(of: "'", with: "%27")
     guard url.scheme == "blob" else {
@@ -45,37 +46,37 @@ class DownloadContentScriptHandler: TabContentScript {
     return true
   }
   
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: @escaping (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
-    
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message, securityToken: UserScriptManager.securityToken) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
     
     do {
       guard let body = message.body as? [String: Any?] else {
-        return
+        return (nil, nil)
       }
       
       let info = try JSONDecoder().decode(BlobDownloadInfo.self, from: JSONSerialization.data(withJSONObject: body))
       guard let _ = Bytes.decodeBase64(info.base64String) else {
-        return
+        return (nil, nil)
       }
       
       defer {
-        browserViewController?.pendingDownloadWebView = nil
-        Self.blobUrlForDownload = nil
+        Task { @MainActor in
+          browserViewController?.pendingDownloadWebView = nil
+          Self.blobUrlForDownload = nil
+        }
       }
       
       guard let requestedUrl = Self.blobUrlForDownload else {
         Logger.module.error("\(Self.scriptName): no url was requested")
-        return
+        return (nil, nil)
       }
       
       guard requestedUrl == info.url else {
         Logger.module.error("\(Self.scriptName): URL mismatch")
-        return
+        return (nil, nil)
       }
       
       var filename = info.url.absoluteString.components(separatedBy: "/").last ?? "data"
@@ -97,5 +98,7 @@ class DownloadContentScriptHandler: TabContentScript {
     } catch {
       Logger.module.error("\(error.localizedDescription)")
     }
+    
+    return (nil, nil)
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/FaviconScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/FaviconScriptHandler.swift
index a014183d22a..b7e51437c44 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/FaviconScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/FaviconScriptHandler.swift
@@ -35,39 +35,40 @@ class FaviconScriptHandler: NSObject, TabContentScript {
                         in: scriptSandbox)
   }()
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
-    guard let tab = tab else { return }
+  @MainActor
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
+    guard let tab = tab else {
+      return (nil, nil)
+    }
     
-    Task { @MainActor in
-      // Assign default favicon
-      tab.favicon = Favicon.default
-      
-      guard let webView = message.webView,
-            let url = webView.url else {
-        return
-      }
-      
-      // The WebView has a valid URL
-      // Attempt to fetch the favicon from cache
-      let isPrivate = tab.isPrivate
-      tab.favicon = FaviconFetcher.getIconFromCache(for: url) ?? Favicon.default
-      
-      // If this is an internal page, we don't fetch favicons for such pages from Brave-Core
-      guard !InternalURL.isValid(url: url),
-            !(InternalURL(url)?.isSessionRestore ?? false) else {
-        return
-      }
-      
-      // Update the favicon for this tab, from Brave-Core
-      tab.faviconDriver?.webView(webView, scriptMessage: message) { [weak tab] iconUrl, icon in
-        FaviconScriptHandler.updateFavicon(tab: tab,
-                                           url: url,
-                                           isPrivate: isPrivate,
-                                           icon: icon,
-                                           iconUrl: iconUrl)
-      }
+    // Assign default favicon
+    tab.favicon = Favicon.default
+    
+    guard let webView = message.webView,
+          let url = webView.url else {
+      return (nil, nil)
+    }
+    
+    // The WebView has a valid URL
+    // Attempt to fetch the favicon from cache
+    let isPrivate = tab.isPrivate
+    tab.favicon = FaviconFetcher.getIconFromCache(for: url) ?? Favicon.default
+    
+    // If this is an internal page, we don't fetch favicons for such pages from Brave-Core
+    guard !InternalURL.isValid(url: url),
+          !(InternalURL(url)?.isSessionRestore ?? false) else {
+      return (nil, nil)
+    }
+    
+    // Update the favicon for this tab, from Brave-Core
+    tab.faviconDriver?.webView(webView, scriptMessage: message) { [weak tab] iconUrl, icon in
+      FaviconScriptHandler.updateFavicon(tab: tab,
+                                         url: url,
+                                         isPrivate: isPrivate,
+                                         icon: icon,
+                                         iconUrl: iconUrl)
     }
+    return (nil, nil)
   }
   
   private static func updateFavicon(tab: Tab?, url: URL, isPrivate: Bool, icon: UIImage?, iconUrl: URL?) {
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/FindInPageScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/FindInPageScriptHandler.swift
index c2260e21d3e..e00ce5bf4a6 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/FindInPageScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/FindInPageScriptHandler.swift
@@ -28,16 +28,14 @@ class FindInPageScriptHandler: TabContentScript {
   static let scriptSandbox: WKContentWorld = .defaultClient
   static let userScript: WKUserScript? = nil
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
-    
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message, securityToken: UserScriptManager.securityToken) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
     
     guard let body = message.body as? [String: AnyObject] else {
-      return
+      return (nil, nil)
     }
 
     guard let data = body["data"] as? [String: Int] else {
@@ -45,7 +43,7 @@ class FindInPageScriptHandler: TabContentScript {
         Logger.module.error("Could not find a message body or the data did not meet expectations: \(body))")
       }
       
-      return
+      return (nil, nil)
     }
 
     if let currentResult = data["currentResult"] {
@@ -55,5 +53,7 @@ class FindInPageScriptHandler: TabContentScript {
     if let totalResults = data["totalResults"] {
       delegate?.findInPageHelper(self, didUpdateTotalResults: totalResults)
     }
+    
+    return (nil, nil)
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/FocusScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/FocusScriptHandler.swift
index 46969a82d5b..c5c3a3fd1fe 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/FocusScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/FocusScriptHandler.swift
@@ -20,35 +20,40 @@ class FocusScriptHandler: TabContentScript {
   static let scriptSandbox: WKContentWorld = .defaultClient
   static let userScript: WKUserScript? = nil
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
-    
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message, securityToken: UserScriptManager.securityToken) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
 
     guard let body = message.body as? [String: AnyObject] else {
-      return Logger.module.error("FocusHelper.js sent wrong type of message")
+      Logger.module.error("FocusHelper.js sent wrong type of message")
+      return (nil, nil)
     }
 
     guard let data = body["data"] as? [String: String] else {
-      return Logger.module.error("FocusHelper.js sent wrong type of message")
+      Logger.module.error("FocusHelper.js sent wrong type of message")
+      return (nil, nil)
     }
 
     guard let _ = data["elementType"],
       let eventType = data["eventType"]
     else {
-      return Logger.module.error("FocusHelper.js sent wrong keys for message")
+      Logger.module.error("FocusHelper.js sent wrong keys for message")
+      return (nil, nil)
     }
 
-    switch eventType {
-    case "focus":
-      tab?.isEditing = true
-    case "blur":
-      tab?.isEditing = false
-    default:
-      return Logger.module.error("FocusHelper.js sent unhandled eventType")
+    await MainActor.run {
+      switch eventType {
+      case "focus":
+        tab?.isEditing = true
+      case "blur":
+        tab?.isEditing = false
+      default:
+        return Logger.module.error("FocusHelper.js sent unhandled eventType")
+      }
     }
+    
+    return (nil, nil)
   }
 }
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/LoginsScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/LoginsScriptHandler.swift
index c033d4f8b8a..1e02fb93a58 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/LoginsScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/LoginsScriptHandler.swift
@@ -30,27 +30,26 @@ class LoginsScriptHandler: TabContentScript {
   static let messageHandlerName = "loginsScriptMessageHandler"
   static let userScript: WKUserScript? = nil
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message, securityToken: UserScriptManager.securityToken) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
     
     guard let body = message.body as? [String: AnyObject] else {
-      return
+      return (nil, nil)
     }
 
-    guard let res = body["data"] as? [String: AnyObject] else { return }
-    guard let type = res["type"] as? String else { return }
+    guard let res = body["data"] as? [String: AnyObject],
+          let type = res["type"] as? String else { return (nil, nil) }
 
     // Check to see that we're in the foreground before trying to check the logins. We want to
     // make sure we don't try accessing the logins database while we're backgrounded to avoid
     // the system from terminating our app due to background disk access.
     //
     // See https://bugzilla.mozilla.org/show_bug.cgi?id=1307822 for details.
-    guard UIApplication.shared.applicationState == .active && !profile.isShutdown else {
-      return
+    guard await UIApplication.shared.applicationState == .active && !profile.isShutdown else {
+      return (nil, nil)
     }
 
     // We don't use the WKWebView's URL since the page can spoof the URL by using document.location
@@ -59,26 +58,24 @@ class LoginsScriptHandler: TabContentScript {
       // Since responses go to the main frame, make sure we only listen for main frame requests
       // to avoid XSS attacks.
       if type == "request" {
-        passwordAPI.getSavedLogins(for: url, formScheme: .typeHtml) { [weak self] logins in
-          guard let self = self else { return }
-
-          if let requestId = res["requestId"] as? String {
-            self.autoFillRequestedCredentials(
-              formSubmitURL: res["formSubmitURL"] as? String ?? "",
-              logins: logins,
-              requestId: requestId,
-              frameInfo: message.frameInfo)
-          }
+        let logins = await passwordAPI.savedLogins(for: url, formScheme: .typeHtml)
+        if let requestId = res["requestId"] as? String {
+          await self.autoFillRequestedCredentials(
+            formSubmitURL: res["formSubmitURL"] as? String ?? "",
+            logins: logins,
+            requestId: requestId,
+            frameInfo: message.frameInfo)
         }
       } else if type == "submit" {
         if Preferences.General.saveLogins.value {
-          updateORSaveCredentials(for: url, script: res)
+          await updateORSaveCredentials(for: url, script: res)
         }
       }
     }
+    return (nil, nil)
   }
 
-  private func updateORSaveCredentials(for url: URL, script: [String: Any]) {
+  private func updateORSaveCredentials(for url: URL, script: [String: Any]) async {
     guard let scriptCredentials = passwordAPI.fetchFromScript(url, script: script),
       let username = scriptCredentials.usernameValue,
       scriptCredentials.usernameElement != nil,
@@ -94,41 +91,34 @@ class LoginsScriptHandler: TabContentScript {
       return
     }
 
-    passwordAPI.getSavedLogins(for: url, formScheme: .typeHtml) { [weak self] logins in
-      guard let self = self else { return }
-
-      for login in logins {
-        guard let usernameLogin = login.usernameValue else {
-          continue
-        }
-
-        if usernameLogin.caseInsensitivelyEqual(to: username) {
-          if password == login.passwordValue {
-            return
-          }
+    let logins = await passwordAPI.savedLogins(for: url, formScheme: .typeHtml)
+    for login in logins {
+      guard let usernameLogin = login.usernameValue else {
+        continue
+      }
 
-          self.showUpdatePrompt(from: login, to: scriptCredentials)
-          return
-        } else {
-          self.showAddPrompt(for: scriptCredentials)
+      if usernameLogin.caseInsensitivelyEqual(to: username) {
+        if password == login.passwordValue {
           return
         }
-      }
 
-      self.showAddPrompt(for: scriptCredentials)
+        await self.showUpdatePrompt(from: login, to: scriptCredentials)
+        return
+      }
     }
+
+    await self.showAddPrompt(for: scriptCredentials)
   }
 
+  @MainActor
   private func showAddPrompt(for login: PasswordForm) {
     addSnackBarForPrompt(for: login, isUpdating: false) { [weak self] in
       guard let self = self else { return }
-
-      DispatchQueue.main.async {
-        self.passwordAPI.addLogin(login)
-      }
+      self.passwordAPI.addLogin(login)
     }
   }
 
+  @MainActor
   private func showUpdatePrompt(from old: PasswordForm, to new: PasswordForm) {
     addSnackBarForPrompt(for: new, isUpdating: true) { [weak self] in
       guard let self = self else { return }
@@ -137,6 +127,7 @@ class LoginsScriptHandler: TabContentScript {
     }
   }
 
+  @MainActor
   private func addSnackBarForPrompt(for login: PasswordForm, isUpdating: Bool, _ completion: @escaping () -> Void) {
     guard let username = login.usernameValue else {
       return
@@ -182,6 +173,7 @@ class LoginsScriptHandler: TabContentScript {
     }
   }
 
+  @MainActor
   private func autoFillRequestedCredentials(formSubmitURL: String, logins: [PasswordForm], requestId: String, frameInfo: WKFrameInfo) {
     let securityOrigin = frameInfo.securityOrigin
 
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/NightModeScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/NightModeScriptHandler.swift
index 70daf6ce820..9ff24b7583d 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/NightModeScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/NightModeScriptHandler.swift
@@ -32,10 +32,12 @@ class NightModeScriptHandler: TabContentScript {
                         in: scriptSandbox)
   }()
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: @escaping (Any?, String?) -> Void) {
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     // Do nothing.
+    return (nil, nil)
   }
 
+  @MainActor
   static func setNightMode(tabManager: TabManager, enabled: Bool) {
     Preferences.General.nightModeEnabled.value = enabled
 
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/ReaderModeScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/ReaderModeScriptHandler.swift
index 52ad743ada6..1d46ab0ca39 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/ReaderModeScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/ReaderModeScriptHandler.swift
@@ -281,16 +281,14 @@ class ReaderModeScriptHandler: TabContentScript {
     delegate?.readerMode(self, didParseReadabilityResult: readabilityResult, forTab: tab)
   }
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
-    
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message, securityToken: UserScriptManager.securityToken) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
     
     guard let body = message.body as? [String: AnyObject] else {
-      return
+      return (nil, nil)
     }
 
     if let msg = body["data"] as? Dictionary<String, Any> {
@@ -313,8 +311,11 @@ class ReaderModeScriptHandler: TabContentScript {
         }
       }
     }
+    
+    return (nil, nil)
   }
 
+  @MainActor
   var style: ReaderModeStyle = DefaultReaderModeStyle {
     didSet {
       if state == ReaderModeState.active {
@@ -325,6 +326,7 @@ class ReaderModeScriptHandler: TabContentScript {
     }
   }
 
+  @MainActor
   static func cache(for tab: Tab?) -> ReaderModeCache {
     switch TabType.of(tab) {
     case .regular:
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/ResourceDownloadScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/ResourceDownloadScriptHandler.swift
index 4ab5f22d92e..b6226a67739 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/ResourceDownloadScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/ResourceDownloadScriptHandler.swift
@@ -57,12 +57,11 @@ class ResourceDownloadScriptHandler: TabContentScript {
                         in: scriptSandbox)
   }()
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
-    
+  @MainActor
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
 
     do {
@@ -71,8 +70,10 @@ class ResourceDownloadScriptHandler: TabContentScript {
     } catch {
       tab?.temporaryDocument?.onDocumentDownloaded(document: nil, error: error)
     }
+    return (nil, nil)
   }
 
+  @MainActor
   static func downloadResource(for tab: Tab, url: URL) {
     tab.webView?.evaluateSafeJavaScript(functionName: "window.__firefox__.downloadManager.download", args: [url.absoluteString], contentWorld: self.scriptSandbox) { _, error in
       if let error = error {
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/SiteStateListenerScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/SiteStateListenerScriptHandler.swift
index 4947e73d0f5..326a7eb6f26 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/SiteStateListenerScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/SiteStateListenerScriptHandler.swift
@@ -41,17 +41,15 @@ class SiteStateListenerScriptHandler: TabContentScript {
                         in: scriptSandbox)
   }()
   
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: @escaping (Any?, String?) -> Void) {
-    defer { replyHandler(nil, nil) }
-    
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     if !verifyMessage(message: message) {
       assertionFailure("Missing required security token.")
-      return
+      return (nil, nil)
     }
     
-    guard let tab = tab, let webView = tab.webView else {
+    guard let tab = tab, let webView = await tab.webView else {
       assertionFailure("Should have a tab set")
-      return
+      return (nil, nil)
     }
     
     do {
@@ -59,10 +57,10 @@ class SiteStateListenerScriptHandler: TabContentScript {
       let dto = try JSONDecoder().decode(MessageDTO.self, from: data)
       
       guard let frameURL = URL(string: dto.data.windowURL) else {
-        return
+        return (nil, nil)
       }
       
-      if let pageData = tab.currentPageData {
+      if let pageData = await tab.currentPageData {
         Task { @MainActor in
           let domain = pageData.domain(persistent: !tab.isPrivate)
           guard domain.isShieldExpected(.AdblockAndTp, considerAllShieldsOption: true) else { return }
@@ -83,6 +81,8 @@ class SiteStateListenerScriptHandler: TabContentScript {
       assertionFailure("Invalid type of message. Fix the `SiteStateListenerScript.js` script")
       Logger.module.error("\(error.localizedDescription)")
     }
+    
+    return (nil, nil)
   }
   
   @MainActor private func makeSetup(from modelTuples: [AdBlockStats.CosmeticFilterModelTuple], isAggressive: Bool) throws -> UserScriptType.SelectorsPollerSetup {
diff --git a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/WindowRenderScriptHandler.swift b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/WindowRenderScriptHandler.swift
index 45856b1911b..be7588e8b2e 100644
--- a/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/WindowRenderScriptHandler.swift
+++ b/Sources/Brave/Frontend/UserContent/UserScripts/Scripts_Dynamic/ScriptHandlers/Sandboxed/WindowRenderScriptHandler.swift
@@ -31,11 +31,14 @@ class WindowRenderScriptHandler: TabContentScript {
                         in: scriptSandbox)
   }()
 
-  func userContentController(_ userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage, replyHandler: (Any?, String?) -> Void) {
+  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) async -> (Any?, String?) {
     // Do nothing with the messages received.
     // For now.. It's useful for debugging though.
+    
+    return (nil, nil)
   }
 
+  @MainActor
   static func executeScript(for tab: Tab) {
     tab.webView?.evaluateSafeJavaScript(functionName: "window.__firefox__.\(resizeWindowFunction).resizeWindow", contentWorld: scriptSandbox)
   }
diff --git a/Sources/Brave/Helpers/TabEventHandlers.swift b/Sources/Brave/Helpers/TabEventHandlers.swift
index eea078542a5..701ca272c9a 100644
--- a/Sources/Brave/Helpers/TabEventHandlers.swift
+++ b/Sources/Brave/Helpers/TabEventHandlers.swift
@@ -5,6 +5,7 @@
 import Foundation
 import Shared
 
+@MainActor
 class TabEventHandlers {
   static func create(with prefs: Prefs) -> [TabEventHandler] {
     return [
diff --git a/Sources/Brave/Helpers/UserActivityHandler.swift b/Sources/Brave/Helpers/UserActivityHandler.swift
index 832f6fb6af6..3d79ca3c18c 100644
--- a/Sources/Brave/Helpers/UserActivityHandler.swift
+++ b/Sources/Brave/Helpers/UserActivityHandler.swift
@@ -13,6 +13,7 @@ private let browsingActivityType: String = "com.brave.ios.browsing"
 
 private let searchableIndex = CSSearchableIndex(name: "firefox")
 
+@MainActor
 class UserActivityHandler {
   private var tabObservers: TabObservers!
 
diff --git a/Sources/Brave/Shortcuts/ActivityShortcutManager.swift b/Sources/Brave/Shortcuts/ActivityShortcutManager.swift
index 6c60d37af0d..d47377f44be 100644
--- a/Sources/Brave/Shortcuts/ActivityShortcutManager.swift
+++ b/Sources/Brave/Shortcuts/ActivityShortcutManager.swift
@@ -147,6 +147,7 @@ public class ActivityShortcutManager: NSObject {
     }
   }
 
+  @MainActor
   private func handleActivityDetails(type: ActivityType, using bvc: BrowserViewController) {
     switch type {
     case .newTab:
diff --git a/Sources/Favicon/FaviconFetcher.swift b/Sources/Favicon/FaviconFetcher.swift
index 2332ac9b8d5..c86f4667cb8 100644
--- a/Sources/Favicon/FaviconFetcher.swift
+++ b/Sources/Favicon/FaviconFetcher.swift
@@ -44,6 +44,7 @@ public class FaviconFetcher {
   /// 4. Fetch Monogram Icons
   /// Notes: Does NOT make a request to fetch icons from the page.
   ///      Requests are only made in FaviconScriptHandler, when the user visits the page.
+  nonisolated
   public static func loadIcon(url: URL, kind: FaviconFetcher.Kind = .smallIcon, persistent: Bool) async throws -> Favicon {
     try Task.checkCancellation()
     
@@ -80,7 +81,7 @@ public class FaviconFetcher {
   /// Creates a monogram Favicon with the following conditions
   /// 1. If `monogramString` is not null, it is used to render the Favicon image.
   /// 2. If `monogramString` is null, the first character of the URL's domain is used to render the Favicon image.
-  public static func monogramIcon(url: URL, monogramString: Character? = nil, persistent: Bool) async throws -> Favicon {
+  nonisolated public static func monogramIcon(url: URL, monogramString: Character? = nil, persistent: Bool) async throws -> Favicon {
     try Task.checkCancellation()
     
     if let favicon = getFromCache(for: url) {
diff --git a/Sources/Playlist/PlaylistMediaStreamer.swift b/Sources/Playlist/PlaylistMediaStreamer.swift
index 50eb11c9373..b7f83a1e662 100644
--- a/Sources/Playlist/PlaylistMediaStreamer.swift
+++ b/Sources/Playlist/PlaylistMediaStreamer.swift
@@ -110,6 +110,7 @@ public class PlaylistMediaStreamer {
       }
       
       let newItem = await webLoader.load(url: url)
+      webLoader.stop()
       webLoader.removeFromSuperview()
       self.webLoader = nil
       
diff --git a/Sources/Playlist/PlaylistSharedFolder.swift b/Sources/Playlist/PlaylistSharedFolder.swift
index 12642a1ba13..e206a17f4df 100644
--- a/Sources/Playlist/PlaylistSharedFolder.swift
+++ b/Sources/Playlist/PlaylistSharedFolder.swift
@@ -159,10 +159,8 @@ public struct PlaylistSharedFolderNetwork {
       }
       
       let webLoader = webLoaderFactory.makeWebLoader()
-//      let webLoader = PlaylistWebLoader().then {
       viewForInvisibleWebView.insertSubview(webLoader, at: 0)
-//      }
-      
+
       guard let newItem = await webLoader.load(url: url) else {
         // Destroy the web loader.
         webLoader.stop()
@@ -170,6 +168,10 @@ public struct PlaylistSharedFolderNetwork {
         throw PlaylistMediaStreamer.PlaybackError.cannotLoadMedia
       }
       
+      // Destroy the web loader.
+      webLoader.stop()
+      webLoader.removeFromSuperview()
+      
       return await withCheckedContinuation { continuation in
         PlaylistManager.shared.getAssetDuration(item: newItem) { duration in
           let item = PlaylistInfo(name: item.name,
@@ -184,10 +186,6 @@ public struct PlaylistSharedFolderNetwork {
                                   tagId: item.tagId,
                                   order: item.order,
                                   isInvisible: newItem.isInvisible)
-          
-          // Destroy the web loader when the callback is complete.
-          webLoader.stop()
-          webLoader.removeFromSuperview()
           continuation.resume(returning: item)
         }
       }