[synthetics] Add synthetics troubleshooting page

docs/en/observability/index.asciidoc

@@ -142,6 +142,8 @@ include::synthetics-support-matrix.asciidoc[leveloffset=+2]
 
 include::synthetics-security-encryption.asciidoc[leveloffset=+2]
 
+include::synthetics-troubleshooting.asciidoc[leveloffset=+2]
+
 // Uptime
 include::uptime-intro.asciidoc[leveloffset=+1]
 

docs/en/observability/synthetics-troubleshooting.asciidoc

@@ -0,0 +1,83 @@
+[[synthetics-troubleshooting]]
+= Troubleshooting Synthetics
+
+++++
+<titleabbrev>Troubleshooting</titleabbrev>
+++++
+
+[discrete]
+[[synthetics-troubleshooting-local-debugging]]
+= Local debugging
+
+For debugging synthetic tests locally, you can set an environment variable,
+`DEBUG=synthetics`, to capture Synthetics agent logs when using the
+<<synthetics-command-reference,Synthetics CLI>>.
+
+[discrete]
+[[synthetics-troubleshooting-common-issues]]
+= Common issues
+
+[discrete]
+[[synthetics-troubleshooting-missing-api-key]]
+== Monitors stopped running after upgrading to 8.8.0 or above
+
+Synthetic monitors will stop running if you have gone through this workflow:
+
+. Enabled Monitor Management (in the {uptime-app}) prior to 8.6.0.
+. Created a synthetic monitor that is configured to run on Elastic's global managed infrastructure.
+. Upgraded to 8.8.0 or above.
+
+This happens because the permissions granted by clicking *Enable Monitor Management* in versions prior to
+8.6.0 are not sufficient in versions 8.8.0 and above.
+
+To fix this, a user with <<synthetics-role-setup,admin permissions>> needs to visit the {synthetics-app}
+in {kib}. In 8.8.0 and above, the equivalent of "enabling monitor management" happens automatically in the
+background when a user with <<synthetics-role-setup,admin permissions>> visits the {synthetics-app}.
+
+If a user _without_ <<synthetics-role-setup,admin permissions>> visits the {synthetics-app} before an admin
+has visited it, the user will see a note that says "Only administrators can enable this feature". That
+note will persist until an admin user visits the {synthetics-app}.
+
+[discrete]
+[[synthetics-troubleshooting-no-agent-running]]
+== No results from a monitor configured to run on a {private-location}
+
+If you have created a {private-location} and configured a monitor to run on that {private-location},
+but don't see any results for that monitor in the {synthetics-app}, make sure there is an agent
+configured to run against the agent policy.
+
+[NOTE]
+=====
+If you attempt to assign an agent policy to a {private-location} _before_ configuring an agent to run
+against the agent policy, you will see a note in the {synthetics-app} UI that the selected agent policy
+has no agents.
+=====
+
+When creating a {private-location}, you have to:
+
+. <<synthetics-private-location-fleet-agent>>.
+. <<synthetics-private-location-connect,Connect {fleet} to the {stack}>> and enroll an {agent} in {fleet}.
+. <<synthetics-private-location-add>> in the {synthetics-app}.
+
+If you do not complete the second item, no agents will be configured to run against the agent policy, and
+any monitors configured to run on that {private-location} won't be able to run so there will be no results
+in the {synthetics-app}.
+
+To fix this, make sure there is an agent configured to run against the agent policy.
+
+[discrete]
+[[synthetics-troubleshooting-get-help]]
+= Get help
+
+[discrete]
+[[synthetics-troubleshooting-support]]
+== Elastic Support
+
+include::troubleshooting.asciidoc[tag=support]
+
+[discrete]
+[[synthetics-troubleshooting-discussion]]
+== Discussion forum
+
+For other questions and feature requests, visit our
+{forum}/c/observability/synthetics/75[discussion forum].

docs/en/observability/troubleshooting.asciidoc

@@ -17,13 +17,15 @@ Use the following tools in {kib} to troubleshoot issues across {observability} a
 [[troubleshooting-support]]
 === Elastic Support
 
+// tag::support[]
 We offer a support experience unlike any other.
 Our team of professionals 'speak human and code' and love making your day.
 https://www.elastic.co/subscriptions[Learn more about subscriptions].
+// end::support[]
 
 [float]
 [[troubleshooting-forum]]
 === Discussion forum
 
 For other questions and feature requests,
-visit our https://discuss.elastic.co/c/observability[discussion forum].
+visit our https://discuss.elastic.co/c/observability[discussion forum].