Sharepoint 2013 user profile sync not working

Symptoms
You can't start the User Profile Synchronization service in Microsoft SharePoint Server 2013. The service shows a status of either Starting or Stopped. Additionally, the following error entry is logged in the ULS log:

Output

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OWSTIMER.EXE (0x2B80) 0x3370 SharePoint Portal Server User Profiles g144 Unexpected Failed to set the new Service Broker on database <SyncDB> on server <ServerName>. Exception: The operation cannot be performed on database <SyncDB> because it is involved in a database mirroring session or an availability group. Some operations are not allowed on a database that is participating in a database mirroring session or in an availability group. ALTER DATABASE statement failed. ALTER DATABASE statement failed.
OWSTIMER.EXE (0x2B80) 0x3370 SharePoint Portal Server User Profiles 9sip High UserProfileApplication.SynchronizeMIIS: Failed to configure MIIS post database, will attempt during next rerun. Exception: System.Data.SqlClient.SqlException (0x80131904): The operation cannot be performed on database <SyncDB> because it is involved in a database mirroring session or an availability group. Some operations are not allowed on a database that is participating in a database mirroring session or in an availability group. ALTER DATABASE statement failed. ALTER DATABASE statement failed.
at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
at System.Data.SqlClient.SqlCommand.RunExecuteNonQueryTds(String methodName, Boolean async, Int32 timeout, Boolean asyncWrite)
at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean& usedCache, Boolean asyncWrite, Boolean inRetry)
at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
at Microsoft.Office.Server.Data.SqlSession.ExecuteNonQuery(SqlCommand command)
at Microsoft.Office.Server.Administration.SynchronizationDatabase.EnableServiceBroker()
at Microsoft.Office.Server.Administration.UserProfileApplication.SetupSynchronizationService(ProfileSynchronizationServiceInstance profileSyncInstance)
ClientConnectionId:<Id> Error Number:1468,State:1,Class:16.
OWSTIMER.EXE (0x2B80) 0x3370 SharePoint Portal Server User Profiles 9i1u Medium UserProfileApplication.SynchronizeMIIS: End setup for 'User Profile Service Application'.
Cause
The issue occurs if the synchronization database is involved in a database mirroring session or an availability group.

Resolution
To resolve the issue, follow these steps:

Remove the <SyncDB> synchronization database from the database mirroring session or the availability group.
Stop the User Profile Synchronization service.
Restart the User Profile Synchronization service.
Restore the <SyncDB> synchronization database to the availability group.