Bug 2407003

This bug happened also on my second Fedora computer.

Maybe it is relevant that I have been upgrading the computers for several years, I think at least since 2017.

I'm curious what your output of "authselect current" would be. Had a similar issue, also on a system with many upgrades, but a different solution: https://discussion.fedoraproject.org/t/no-login-screen-after-upgrade-to-f43-solved-authselect-was-never-set-up-on-a-system-upgraded-through-many-versions/170594

On both systems with this bug:

$ authselect current
No existing configuration detected.

Description of problem:
After upgrading from Fedora 42 to Fedora 43 my computer did not show the graphical window with users to log in into GNOME any more.
I tested booting with my old kernels and rescue, the same happened.
Tried to login via Ctrl-alt-f2,f3,f4, I couldn't write usernames on these screens.

I have a deskside computer, that has been running Fedora about 10 years ( upgrade twice a year).

The Gnome-login started, when I saved the shadow file and I could login.
Rebooted and started a normal session.
The work-around did it.

(In reply to Jan Vlug from comment #0)
> Description of problem:
> After upgrading from Fedora 42 to Fedora 43 my computer did not show the
> graphical window with users to log in into GNOME any more.
> 
> The system was "just hanging" with a black screen.
> 
> I still could ssh into the system.
> 
> The solution is given here:
> https://discussion.fedoraproject.org/t/fedora-43-upgrade-failed-had-to-
> manually-reboot-now-gdm-coredumps/170463/3
> 
> Which is:
> sudo vi /etc/shadow
> 
> add a line at the bottom of the file that looks like the following:
> 
> gdm-greeter:!:20102::::::
> 
> save the file via :wq!
> 
> reboot

I have got this issue to on my Fedora 43 : 
Updating from kernel-6.17.7-300.fc43.x86_64 to kernel-6.17.8-300.fc43.x86_64
And adding this to /etc/shadow fixed it.
gdm-greeter:!:20102:::::: 

---
I see there gdm is coredumping each time and I still have the coredumps if you need.

adding this if it helps:

$ authselect current
Profile ID: sssd
Enabled features:
- with-mdns4

It looks like gdm fails to set up the session of a login screen
because the gdm-greeter dynamic users can't be found. 

Those should be found from systemd-userdbd. From what I've seen 
in related issues, systemd-userdbd might not be properly
set up by sssd.

Is this something known? @ipedrosa

No, I don't think there's any relation between this issue and SSSD, but the problem seems to be related to authselect.

In recent Fedora releases /etc/nsswitch.conf is owned by authselect, and thus this package should be installed and properly configured for the system to provide users coming from systemd-userdbd. I'm assuming that's where gdm-greeter dynamic user is located.

I solved it by adding systemd to the shadow line in /etc/nsswitch.conf (suggested by user einer) in the discussion at [1]

shadow: files systemd

[1] https://discussion.fedoraproject.org/t/fedora-43-upgrade-failed-had-to-manually-reboot-now-gdm-coredumps/170463/17