Sometimes after a vSphere upgrade Update Manager (VUM) can fail with the following error:
There was an error connecting VMware vSphere Update Manager - [vcenter.example.com:443]. Database temporarily unavailable or has network problems.
The easiest way is to reconfigure the VUM using the
VMwareUpdateManagerUtility.exe utility installed in the VMware Update Manager program path (usually
C:\Program Files (x86)\VMware\Infrastructure\Update Manager):
Then restart the VMware vSphere Update Manager service.