I replaced my Avira AV with Bitdefender to see if that changes anything, but no chance.
Update still does not work. :-(
No MS official help seems to be coming here so I assume, that support for Windows 7 already ended now
and not on January 14th 2020?
That's the way I see it, too. Support has already ended. So I'm not waiting until January to disconnect Windows from the Internet. I will keep my Linux installation and boot to Windows 7 only when I need to use a specific program, which is rarely now. No chance of going to 10. Bye bye Microsoft!