Problem with TLShell Tex Live Manager

[M. Münch]

> When I open TLShell Tex Live Manager, it shows "back end gone" and
> forces me to quit (as shown in the picture).
> The update-tlmgr-latest.exe does not work. How can I solve
> this problem?

If you happen to run TLShell Tex Live Manager' GUI under Windows 11 and
have a Windows username which contains anything else that a to z (or A
to Z), then that is a known behaviour.

tlmgr update [plus parameters] at the command line should work just fine
in that case.