Not sure if I filed this bug in the right Component, feel free to reassign.

Tumbleweed 20230301. Didn't happen in February versions.

When trying to boot and log in to X11, an error page (white with black text)
appears (on tty7), as follows:

(screen icon with unhappy face)
Oh, no! Something has gone wrong.
A problem has occurred and the system can't recover. Please contact a system
administrator.

Ctrl-Alt-F1 to Ctrl-Alt-F6 still work and I can log in in text mode.

Temporary solution:
- Manually edit /etc/sysconfig/displaymanager and give DISPLAYMANAGER_AUTOLOGIN
a nonemty value for an existing username. This user, even if root, will be
logged in automatically into X without needing a password.
- Manually edit /etc/sysconfig/windowmanager and make sure DEFAULT_WM is
defaulted.
- Run update-alternatives --config default-xsession.desktop and select
something else than gnome or plasma5. With lxde it works, though AFAICT only
two virtual desktops will be available and everything will be displayed bigger
than it used to be.
- Close X11 and start it again (e.g. init 3 followed by init 5).

Results: You are now logged into the GUI, bypassing the X11 login form. The
error screen remains visible on /dev/tty7. It is still not possible to log into
a different user in GUI mode, other than by changing the value of
DISPLAYMANAGER_AUTOLOGIN in /etc/sysconfig/displaymanager then closing down and
restarting X11.