I think I encountered the same problem since this morning with gdm3 version 49-1.6, but am not sure it is really the same error.
When rebooting the commputer, the screen flashes a little but remain black, without displaying the user selection widget, and it is impossible to switch to a console screen using Ctrl-Alt-Fn. The only thing that worked was rebooting using Ctrl-Alt-Suppr, and then switching to recovery session. It seems gdm was the culprit as journalctl showed this: nov. 07 16:47:38 lehrin gdm-launch-environment][2449]: pam_unix(gdm- launch-environment:session): session opened for user gdm- greeter(uid=60578) by (uid=0) nov. 07 16:47:38 lehrin gdm3[2442]: Gdm: GdmSession: no session desktop files installed, aborting... nov. 07 16:47:38 lehrin systemd[1]: gdm.service: Main process exited, code=killed, status=5/TRAP nov. 07 16:47:38 lehrin systemd[1]: gdm.service: Failed with result 'signal'. nov. 07 16:47:38 lehrin systemd[1]: gdm.service: Triggering OnFailure= dependencies. nov. 07 16:47:39 lehrin systemd[1]: gdm.service: Scheduled restart job, restart counter is at 2. nov. 07 16:47:39 lehrin systemd[1]: Starting gdm.service - GNOME Display Manager... nov. 07 16:47:40 lehrin systemd[1]: Started gdm.service - GNOME Display Manager. nov. 07 16:47:40 lehrin gdm-launch-environment][2502]: pam_unix(gdm- launch-environment:session): session opened for user gdm- greeter(uid=60578) by (uid=0) nov. 07 16:47:40 lehrin gdm3[2496]: Gdm: GdmSession: no session desktop files installed, aborting... nov. 07 16:47:40 lehrin systemd[1]: gdm.service: Main process exited, code=killed, status=5/TRAP nov. 07 16:47:40 lehrin systemd[1]: gdm.service: Failed with result 'signal'. nov. 07 16:47:40 lehrin systemd[1]: gdm.service: Triggering OnFailure= dependencies. nov. 07 16:47:41 lehrin systemd[1]: gdm.service: Scheduled restart job, restart counter is at 3. nov. 07 16:47:41 lehrin systemd[1]: Starting gdm.service - GNOME Display Manager... nov. 07 16:47:41 lehrin systemd[1]: Started gdm.service - GNOME Display Manager. nov. 07 16:47:41 lehrin gdm-launch-environment][2527]: pam_unix(gdm- launch-environment:session): session opened for user gdm- greeter(uid=60578) by (uid=0) nov. 07 16:47:41 lehrin gdm3[2521]: Gdm: GdmSession: no session desktop files installed, aborting... nov. 07 16:47:41 lehrin systemd[1]: gdm.service: Main process exited, code=killed, status=5/TRAP nov. 07 16:47:41 lehrin systemd[1]: gdm.service: Failed with result 'signal'. nov. 07 16:47:41 lehrin systemd[1]: gdm.service: Triggering OnFailure= dependencies. nov. 07 16:47:42 lehrin systemd[1]: gdm.service: Scheduled restart job, restart counter is at 4. nov. 07 16:47:42 lehrin systemd[1]: Starting gdm.service - GNOME Display Manager... nov. 07 16:47:42 lehrin systemd[1]: Started gdm.service - GNOME Display Manager. nov. 07 16:47:42 lehrin gdm-launch-environment][2554]: pam_unix(gdm- launch-environment:session): session opened for user gdm- greeter(uid=60578) by (uid=0) nov. 07 16:47:42 lehrin gdm3[2548]: Gdm: GdmSession: no session desktop files installed, aborting... nov. 07 16:47:42 lehrin systemd[1]: gdm.service: Main process exited, code=killed, status=5/TRAP nov. 07 16:47:42 lehrin systemd[1]: gdm.service: Failed with result 'signal'. nov. 07 16:47:42 lehrin systemd[1]: gdm.service: Triggering OnFailure= dependencies. nov. 07 16:47:43 lehrin systemd[1]: gdm.service: Scheduled restart job, restart counter is at 5. nov. 07 16:47:43 lehrin systemd[1]: gdm.service: Start request repeated too quickly. nov. 07 16:47:43 lehrin systemd[1]: gdm.service: Failed with result 'signal'. nov. 07 16:47:43 lehrin systemd[1]: Failed to start gdm.service - GNOME Display Manager. nov. 07 16:47:43 lehrin systemd[1]: gdm.service: Triggering OnFailure= dependencies. Searching for "GdmSession: no session desktop files installed" error, I found some hints about gnome 49 dropping X support and /usr/share/wayland-sessions vs /usr/share/xsessions, but on my computer, both exist: (lehrin) luc% ls -l /usr/share/wayland-sessions/ total 56 -rw-r--r-- 1 root root 8240 31 oct. 13:34 gnome-classic.desktop -rw-r--r-- 1 root root 8364 31 oct. 13:34 gnome-classic- wayland.desktop -rw-r--r-- 1 root root 8014 31 oct. 14:23 gnome.desktop -rw-r--r-- 1 root root 8570 31 oct. 14:23 gnome-wayland.desktop -rw-r--r-- 1 root root 9175 22 août 17:07 xfce-wayland.desktop (lehrin) luc% ls -l /usr/share/xsessions/ total 16 -rw-r--r-- 1 root root 86 21 juin 2024 lightdm-xsession.desktop -rw-r--r-- 1 root root 10257 22 août 17:07 xfce.desktop (lehrin) luc% The only way I found to at least get an environment was to first uncomment "WaylandEnable=false" in /etc/gdm3/daemon.conf, which at least allowed to switch to a console, and then to install task-xfce- desktop in order to avoid gdm. I tried using "dbus-run-session -- gnome-shell --display-server --wayland" as proposed above, but it didn't work. For now, gdm3 seems impossible to use on my computer. best regards, Luc
