diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0443656..c9a6793 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,13 @@
 # Changelog
 
+## 4.21.6 (Sep 26, 2024)
+
+
+## Improvements
+- Improved `SendbirdChat.initialize()` and `SendbirdChat.connect()` speed when `isLocalCachingEnabled` is true
+- Improved handling events related to reactions
+- Fixed a bug where a channel gets unexpectedly unhidden upon receiving a new message
+
 ## 4.21.5 (Sep 23, 2024)
 
 
diff --git a/Package.swift b/Package.swift
index 8b2c68d..b771210 100644
--- a/Package.swift
+++ b/Package.swift
@@ -15,8 +15,8 @@ let package = Package(
     targets: [
         .binaryTarget(
             name: "SendbirdChatSDK",
-            url: "https://github.com/sendbird/sendbird-chat-sdk-ios/releases/download/4.21.5/SendbirdChatSDK.xcframework.zip",
-            checksum: "3b239608b6af4672b336e7bb64aa5923befb6e3f8e0bedd59d2d0a33bced0553"
+            url: "https://github.com/sendbird/sendbird-chat-sdk-ios/releases/download/4.21.6/SendbirdChatSDK.xcframework.zip",
+            checksum: "8fa94b801d0164b5241ff0b27165677ecd6e01eae604e15fc04b1259c9dbd482"
         ),
     ]
 )
diff --git a/SendbirdChatSDK.podspec b/SendbirdChatSDK.podspec
index 30b75cb..c5e54c0 100644
--- a/SendbirdChatSDK.podspec
+++ b/SendbirdChatSDK.podspec
@@ -1,7 +1,7 @@
 
 Pod::Spec.new do |s|
   s.name         = 'SendbirdChatSDK'
-  s.version      = "4.21.5"
+  s.version      = "4.21.6"
   s.summary      = 'Sendbird Chat iOS Framework'
   s.description  = 'Messaging and Chat API for Mobile Apps and Websites'
   s.homepage     = 'https://sendbird.com'
@@ -16,7 +16,7 @@ Pod::Spec.new do |s|
     'Young Hwang' => 'young.hwang@sendbird.com',
     'Kai Lee' => 'kai.lee@sendbird.com'
   }
-  s.source       = { :http => "https://github.com/sendbird/sendbird-chat-sdk-ios/releases/download/4.21.5/SendbirdChatSDK.zip", :sha1 => "44c9e070f7eec0185aa7ab1e0e4f19ca5899bb0e" }
+  s.source       = { :http => "https://github.com/sendbird/sendbird-chat-sdk-ios/releases/download/4.21.6/SendbirdChatSDK.zip", :sha1 => "7bcb9eec194b09c8ed629373c99c46a81dee64fc" }
   s.requires_arc = true
   s.platform = :ios, '12.0'
   s.documentation_url = 'https://sendbird.com/docs/chat'