gdm3/gdm-session-worker crashed with SIGTRAP logging "GdmSession: no session desktop files installed, aborting..." from get_fallback_session_name from get_default_session_name from get_session_name from get_session_filename from gdm_session_is_wayland_session

StacktraceTop:
 get_fallback_session_name (self=self@entry=0x55c1e2529580) at gdm-session.c:593
 get_default_session_name (self=0x55c1e2529580) at gdm-session.c:619
 get_session_name (self=self@entry=0x55c1e2529580) at gdm-session.c:2426
 get_session_filename (self=self@entry=0x55c1e2529580) at gdm-session.c:2999
 gdm_session_is_wayland_session (self=self@entry=0x55c1e2529580) at gdm-session.c:3014

Status changed to 'Confirmed' because the bug affects multiple users.

I think this looks like the same as:
https://errors.ubuntu.com/problem/b8e7721d0034b2c4a5ddafcac2e1cc55703f9dbd

Also tracking in:
https://errors.ubuntu.com/problem/55afdb022e0f09e32692656f5ec80985acf385cc

And now in:
https://errors.ubuntu.com/problem/f4fce39ac75fb4f87b243f14cb5f8e72f90c2c0f

I have perhaps a clue, I have a app that stopped working (it was OK 2 weeks ago):

./molotov.AppImage
dlopen(): error loading libfuse.so.2

AppImages require FUSE to run.
You might still be able to extract the contents of this AppImage
if you run it with the --appimage-extract option.
See https://github.com/AppImage/AppImageKit/wiki/FUSE
for more information

But when I try to install FUSE, it asks me to remove ubuntu-session !. I remember that I did that some days/weeks ago.

sudo apt install fuse
Lecture des listes de paquets... Fait
Construction de l'arbre des dépendances... Fait
Lecture des informations d'état... Fait
Le paquet suivant a été installé automatiquement et n'est plus nécessaire :
  xwayland
Veuillez utiliser « sudo apt autoremove » pour le supprimer.
Les paquets supplémentaires suivants seront installés :
  libfuse2
Les paquets suivants seront ENLEVÉS :
  fuse3 ubuntu-session xdg-desktop-portal xdg-desktop-portal-gnome
  xdg-desktop-portal-gtk
Les NOUVEAUX paquets suivants seront installés :
  fuse libfuse2
0 mis à jour, 2 nouvellement installés, 5 à enlever et 0 non mis à jour.
Il est nécessaire de prendre 117 ko dans les archives.
Après cette opération, 1 887 ko d'espace disque seront libérés.
Souhaitez-vous continuer ? [O/n]

Thanks, that's great.

On Mon, 13 Feb 2023, 11:45 am Daniel van Vugt, <email address hidden>
wrote:

> ** Description changed:
>
>
> https://errors.ubuntu.com/problem/b8e7721d0034b2c4a5ddafcac2e1cc55703f9dbd
>
> https://errors.ubuntu.com/problem/55afdb022e0f09e32692656f5ec80985acf385cc
>
> https://errors.ubuntu.com/problem/f4fce39ac75fb4f87b243f14cb5f8e72f90c2c0f
>
> ---
>
> - multiseat via udev rules not working gdm upset.
> + This crash occurs when you uninstall all session files (by accident)
> + from the system. To fix it just run:
>
> - ProblemType: Crash
> - DistroRelease: Ubuntu 17.10
> - Package: gdm3 3.26.0-1ubuntu1
> - ProcVersionSignature: Ubuntu 4.12.0-13.14-generic 4.12.10
> - Uname: Linux 4.12.0-13-generic x86_64
> - ApportVersion: 2.20.7-0ubuntu1
> - Architecture: amd64
> - CrashCounter: 1
> - Date: Sun Sep 17 18:12:57 2017
> - ExecutablePath: /usr/sbin/gdm3
> - InstallationDate: Installed on 2017-04-09 (161 days ago)
> - InstallationMedia: Ubuntu 16.10 "Yakkety Yak" - Release amd64
> (20161012.2)
> - ProcCmdline: /usr/sbin/gdm3
> - ProcEnviron:
> - LANG=en_AU.UTF-8
> - LANGUAGE=en_AU:en
> - PATH=(custom, no user)
> - Signal: 5
> - SourcePackage: gdm3
> - StacktraceTop:
> - ()
> - ()
> - ()
> - ()
> - ()
> - Title: gdm3 crashed with signal 5
> - UpgradeStatus: No upgrade log present (probably fresh install)
> - UserGroups:
> + sudo apt install --reinstall ubuntu-session
> +
> + or whatever-session for your preferred Ubuntu flavor.
>
> ** Changed in: gdm3 (Ubuntu)
> Status: Confirmed => Triaged
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1717878
>
> Title:
> gdm3/gdm-session-worker crashed with SIGTRAP logging "GdmSession: no
> session desktop files installed, aborting..." from
> get_fallback_session_name from get_default_session_name from
> get_session_name from get_session_filename from
> gdm_session_is_wayland_session
>
> Status in gdm3 package in Ubuntu:
> Triaged
>
> Bug description:
>
> https://errors.ubuntu.com/problem/b8e7721d0034b2c4a5ddafcac2e1cc55703f9dbd
>
> https://errors.ubuntu.com/problem/55afdb022e0f09e32692656f5ec80985acf385cc
>
> https://errors.ubuntu.com/problem/f4fce39ac75fb4f87b243f14cb5f8e72f90c2c0f
>
> ---
>
> This crash occurs when you uninstall all session files (by accident)
> from the system. To fix it just run:
>
> sudo apt install --reinstall ubuntu-session
>
> or whatever-session for your preferred Ubuntu flavor.
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/ubuntu/+source/gdm3/+bug/1717878/+subscriptions
>
>

I found the solution worked reinstalling sessions.
I noticed when I did that Apr removed fuse and installed fuse3.
It is likely that installing fuse is the cause of the problem.

Indeed I expect the real fix would be in 'fuse'. I'm not sure how gdm could be improved here but keep that task open still so people can find the bug.