Verify if the service account used to run synchronization service exists in your Active Directory. 2. Verify that the service ...

      

1. Verify if the service account used to run synchronization service exists in your Active Directory.
2. Verify that the service account password has not expired.It is recommended that the account should be configured with "password never expires" option.
3. Ensure the service account has right permissions to log into Windows. Check if any group policy is changing the permissions.
4. If the problem persists, contact Microsoft Support.