X session doesn't start. Segmentation fault at address 0x0

[ehm.education]

All of a sudden my uConsole CM4 won’t load into an X session any more. after booting it hangs at a blinking cursor. I can switch to another tty and get a CLI, however. Checking the Xorg log shows a Segmentation fault at address 0x0 error.

I am not knowledgeable enough to proceed from here, but would like to fix the problem, instead of just rewriting the image again.

[guu]

did you

sudo apt update  && sudo apt upgrade 

?

[ehm.education]

Yes, i tried update and upgrade, but it reports everything being up to date.