GDM traps on service start with Fedora 42

XeIaso · April 30, 2025, 7:24pm

Hey,

I’ve ran a system update on Fedora 42 Workstation (GNOME) and GDM throws a trap on boot:

gist.github.com

https://gist.github.com/Xe/b255baa5b79d9e2748ceb89c11dd6167

gistfile1.txt

Apr 30 15:16:25 shiroko systemd[1]: Starting gdm.service - GNOME Display Manager...
Apr 30 15:16:25 shiroko systemd[1]: Started gdm.service - GNOME Display Manager.
Apr 30 15:16:26 shiroko gdm[3198]: Gdm: GdmDisplay: Session never registered, failing
Apr 30 15:16:26 shiroko gdm[3198]: Gdm: Child process -3216 was already dead.
Apr 30 15:16:36 shiroko gdm[3198]: Gdm: GdmSession: no session desktop files installed, aborting...
Apr 30 15:16:36 shiroko systemd-coredump[3504]: Process 3198 (gdm) of user 0 dumped core.
                                                
                                                Module /usr/bin/gdm from rpm gdm-48.0-3.fc42.x86_64
                                                Module libnss_systemd.so.2 from rpm systemd-257.5-2.fc42.x86_64
                                                Module libblkid.so.1 from rpm util-linux-2.40.4-7.fc42.x86_64

This file has been truncated. show original

Additionally this makes NetworkManager not start. I can start Sway from this state, but it does not start XWayland if I do.

I am unable to downgrade to a working state due to facts and circumstances involving RPMFusion not keeping old copies of packages for some reason.

How should I debug this?

XeIaso · April 30, 2025, 8:02pm

I added debug logs to the mix, no debug logs were emitted. I managed to get into a graphical session with lightdm.

/etc/systemd/system/gdm.service.d/override.conf

[Service]
Environment=G_MESSAGES_DEBUG=all

skeller · April 30, 2025, 8:15pm

What version of the gdm package do you have installed? Fedora 42 disabled X11 support for some versions of the package. Tthat could result in this error if only X11 sessions are available for some reason.

XeIaso · April 30, 2025, 8:18pm

dnf info says this is installed: gdm-48.0-3.fc42.x86_64

When I got in via lightdm, the terminal reports I am in a wayland session:

$ env | grep -i wayland
WAYLAND_DISPLAY=wayland-0
XAUTHORITY=/run/user/1000/.mutter-Xwaylandauth.8OYU52
XDG_SESSION_TYPE=wayland

Additionally, /usr/share/wayland-sessions reports wayland sessions are available:

$ ls /usr/share/wayland-sessions/ | cat
gnome-classic.desktop
gnome-classic-wayland.desktop
gnome.desktop
gnome-wayland.desktop
sway.desktop
sway-nvidia.desktop

Additionally, no files are present in /usr/share/xsessions:

ls -la /usr/share/xsessions 
total 0
drwxr-xr-x. 1 root root    0 Jan 15 19:00 .
drwxr-xr-x. 1 root root 5840 Apr 30 15:51 ..

skeller · April 30, 2025, 8:20pm

In that case you are probably missing the gnome-session-xsession package.

XeIaso · April 30, 2025, 8:33pm

I was indeed missing that package. Is there a “globally reinstall all selected groups” command so I can fix any of the other problems that may have crept in?

skeller · April 30, 2025, 8:45pm

sudo dnf group install workstation-product-environment might help, but I’m not sure if gnome-session-xsession would have been installed by that. It is only needed on systems where gdm does not use Wayland and Fedora 42 dropped support for X11 sessions in the default Workstation spin.

XeIaso · May 3, 2025, 2:37am

Installing gnome-session-xsession made GDM not work in Wayland mode, it’s only starting x11 sessions now. I’m probably going to blow away Fedora and install Arch.

tragivictoria · May 3, 2025, 3:13am

Can you make a bug report on Red Hat Bugzilla? That doesn’t sound normal.

XeIaso · May 3, 2025, 3:36am

I can, but I’d need to know what commands I need to run before tomorrow afternoon. I plan to blow away Fedora then and I will not have a backup of the exact system state that is causing these issues.