I found a solution.
- (If you have the opportunity) disconnect all storage media other than the main one, to which you want to install Windows 11.
- In the Windows installation window, when you get to the installation method option, select the “Previous version of the configuration” option, it may also come up as “Launch legacy experience”.
Then it should already let you install Windows 11, and you can reconnect the others storage media.
Unbelievable that Microsoft, desperately looking for people to upgrade from Windows 10, allows such errors.
Come on, this is the Windows Vista of today, which I only upgraded from for the support. I'm glad there are tools that bring back the Windows 10 start menu. A complete mistake to have removed the tiles.
PS: there is a possibility that one of the storage media that you disconnected, does not appear in the file explorer, and that is because Windows 11 does not assign a letter and path to it. This can be fixed by simply running the disk manager, and setting the drive letter manually.