After installing patches on the WSUS server this month (June 2016), the WSUS console wouldn't start, giving a vague message:
Unexpected Error. Please reset the server node and try again.
Event logs also show vague 507 and 7034 messages:
Event 7053 also shows up, however deleting everything from the %appdata%\Microsoft\MMC\ folder does not fix the issue.
Installing KB3159706 turned out to the cause, and completing the post-installation steps on that page fixes the issue and the console loads normally again.
- Run "C:\Program Files\Update Services\Tools\wsusutil.exe" postinstall /servicing from elevated cmd prompt.
- Install Roles/Features, .NET Framework 4.5 Features, under WCF Services, check HTTP Activation.
- Restart WSUS service.