Thanks to everyone who took the time and trouble to make a suggestion! I've tried to follow them. Which means: - I've removed .Net Framework via "Turn Windows features on or off"; - I've downloaded and installed the most recent version of .Net Framework Runtime (4.8.1); - I've removed PatchMyPC.exe from its location om my hard disk and re-copied it (same version, 188.8.131.52) from the Downloads directory to its previous location.
The result of all this is that the error window from .NET Framework now only pops up if I use the switch "/auto" with PatchMyPC. The error message is: "File format is not valid". If I click the "Continue" button in the error window, PatchMyPC does what it should do and exits. If I use PatchMyPC without switches, there is now no error anymore and it remains open. I can live with that, although I like that /auto switch.
I'm using the free version of PatchMyPC, which is why I wasn't familiar with the term "Publisher".
I have the same problem after upgrading to Windows 11. Under Windows 10, PatchMyPC worked fine. I have .NET Framework installed, just like the other users in this thread. I would *highly* appreciate a fix for this problem.