User Profile Sync Stuck on Starting

If your User Profile Sync service Stuck on Starting. First thing you need to do is change the service status to Stop using below Powershell.



Add-PSSnapin Microsoft.SharePoint.Powershell

$TypeName = "User Profile Synchronization Service"

$ServerName = "Server Name"

$Serviceinstance = Get-SPServiceInstance | where-object {$_.TypeName -eq $TypeName -and $_.Server.Address -eq $ServerName}

$Serviceinstance.Unprovision()

Now, Go to Service.msc and check if both  ForefrontIdentityManager Services are disabled.
   

1. Run(Ctrl + R), type mmc.exe 
2. Click on file -> add/remove snap in
3. select Certificates and click Add on Certificates snap-in screen choose Computer account
4. select local computer and click finish
5. click ok on "Add or remove snap-ins" screen
6. go to Console root -> certificates -> Trusted Root Certification authorities -> Certificates -> Select all ForefrontIdentityManager certificates and delete them.
7. Look for FIM certificates in other folder also if you find any delete them.
8. Once all the certificates has been removed. Try to start the UPA sync service.

This time it wont be getting stuck.

Hope this post will help you out :)