If you instal KB3159706 on your WSUS then wondering why it is unable to start, just scroll down on that page and run the manual post configuration steps:
- Open an elevated Command Prompt window, and then run the following command (case sensitive, assume “C” as the system volume):
"C:\Program Files\Update Services\Tools\wsusutil.exe" postinstall /servicing
- Select HTTP Activation under .NET Framework 4.5 Features in the Server Manager Add Roles and Features wizard.
- Restart the WSUS service.
I already did this in the not so far past, but forget to write it down. Now thanks to this post I was able to quickly fix this error.