Illustrator won't open any file

[Isa5FF3]

Illustrator opens completely normally but I can't open or create any file. There are no errors or crashes and there is enough space to save the file. So I'm pretty desperate for any kind of help.

[Monika Gause]

Did you already reboot the computer?

Which version and system is it?

[Isa5FF3]

Yes, but nothing changes. 
I got macOS Big Sur, Version 11.2.3,  I installed the newest version Illustrator --> 25.2.1 and I even tried older versions of Illustrator.

[Monika Gause]

Do you have a printer connected and set up as the default printer?

Illustrator looks for a printer when opening files or creating new ones. It tends to act funky when it doesn't find one.