Situation: 1. A WSUS server within your network may have been decommissioned.
2. A WSUS client has a problem to sync with the WSUS Server.
3. WSUS has a problem to push updates to a WSUS client.
Resolution: Remove the registry entries on WSUS client and reset the Windows Update to defaults. Please refer to this how to:
How to remove a computer from WSUS
