When running the WSUS Server Cleanup Wizard from the MMC snap-in, it can occur that you receive the following WSUS database error:

Error: Database Error
An error occurred when trying to perform a database operation. This can happen if the database is very busy, if the database service is stopped, if the connection to the database is lost, of if the Post-Installation task is not completed successfully. Please contact your system administrator if the problem persists.

Click Reset Server Node to try to connect to the server again.