I have a system which is not working with wayland

In /etc/gdm3/daemon.conf I uncommented the line to force the login screen to use Xorg
WaylandEnable=false

This worked ok with the previous versions of gdm3 (45.0.1) and gnome-shell

With gdm3 and gnome-shell version 47.0-3 it fails to start the gdm.service with error

gdm3[1477]: Gdm: GdmSession: no session desktop files installed, aborting...

Here is extract of systemd journal:

Mon 2024-10-21 15:19:54 CEST systemd[1]: Started gdm.service - GNOME Display Manager.
Mon 2024-10-21 15:19:54 CEST gdm-launch-environment][1580]: pam_unix(gdm-launch-environment:session): session opened for user Debian-gdm(uid=111) by (uid=0)
Mon 2024-10-21 15:19:54 CEST gdm-launch-environment][1580]: pam_systemd(gdm-launch-environment:session): New sd-bus connection (system-bus-pam-systemd-1580) opened.
Mon 2024-10-21 15:19:54 CEST systemd-logind[1207]: New session c1 of user Debian-gdm.
Mon 2024-10-21 15:19:54 CEST (systemd)[1592]: pam_unix(systemd-user:session): session opened for user Debian-gdm(uid=111) by Debian-gdm(uid=0)
Mon 2024-10-21 15:19:54 CEST systemd-logind[1207]: New session 1 of user Debian-gdm.
Mon 2024-10-21 15:19:54 CEST systemd[1]: Started session-c1.scope - Session c1 of User Debian-gdm.
Mon 2024-10-21 15:19:54 CEST gdm3[1477]: Gdm: GdmSession: no session desktop files installed, aborting...
Mon 2024-10-21 15:19:54 CEST kernel: show_signal: 58 callbacks suppressed
Mon 2024-10-21 15:19:54 CEST kernel: traps: gdm3[1477] trap int3 ip:7feb4e7a869a sp:7ffe25b68d90 error:0 in libglib-2.0.so.0.8200.1[6569a,7feb4e761000+9f000]
Mon 2024-10-21 15:19:54 CEST systemd[1]: gdm.service: Main process exited, code=killed, status=5/TRAP
Mon 2024-10-21 15:19:54 CEST systemd[1]: gdm.service: Failed with result 'signal'.
Mon 2024-10-21 15:19:54 CEST systemd[1]: gdm.service: Triggering OnFailure= dependencies.

Seems to work ok now, after installing gnome-session-xsession

Bug can be closed, but more helpful error message, or comment in
daemon.conf would be nice

Control: reopen -1
Control: retitle -1 gdm3: gdm.service fails to start when
WaylandEnable=false if gnome-session-xsession isn't installed

This is https://gitlab.gnome.org/GNOME/gdm/-/issues/881

We might want to consider building GDM with -Dx11-support=false
to avoid this failure case.

I think that forces GDM into Wayland-only mode but users can still log
into the GNOME on Xorg
session or other desktop sessions that don't support Wayland.

Hopefully, all our users should be able to run Wayland for the login
screen, but there are
enough concerns about whether Wayland works for all GNOME users that
we are more hesitant
to stop installing gnome-session-xsession by default like Fedora 42 does.
But gnome-session-xsession is only a Recommends to enable people to
try out that experience.

Thank you,
Jeremy Bícha