** Package changed: gnome-shell (Ubuntu) => mutter (Ubuntu)
** Also affects: mutter (Ubuntu Plucky)
Importance: Undecided
Status: New
** Also affects: mutter (Ubuntu Questing)
Importance: Undecided
Status: New
** Bug watch added: gitlab.gnome.org/GNOME/mutter/-/issues #4310
https://gitlab.gnome.org/GNOME/mutter/-/issues/4310
** Also affects: mutter via
https://gitlab.gnome.org/GNOME/mutter/-/issues/4310
Importance: Unknown
Status: Unknown
** Changed in: mutter (Ubuntu)
Status: Incomplete => Fix Committed
** Changed in: mutter (Ubuntu)
Milestone: None => ubuntu-26.04
** Changed in: mutter (Ubuntu Questing)
Status: New => Triaged
** Changed in: mutter (Ubuntu Questing)
Importance: Undecided => Medium
** Changed in: mutter (Ubuntu Questing)
Milestone: None => questing-updates
** Tags added: desktop-needs-sru fixed-in-mutter-49.1 fixed-upstream
** Description changed:
What I expected to happen:
Even if a Wayland client sends invalid or unsupported window geometry, GNOME
Shell / Mutter should handle it gracefully (e.g. ignore the request or
terminate that client), without crashing the whole desktop session.
What happened instead:
While running a Wayland client that creates a regular toplevel window, GNOME
Shell crashes and the Wayland compositor restarts.
Just before the crash, the journal logs show that Mutter reports invalid
window geometry for an xdg_surface, followed by an assertion failure in
meta_window_set_stack_position_no_sync, and then GNOME Shell exits with
signal 8. Other applications then log “Lost connection to Wayland
compositor”.
Relevant journal messages:
- meta_window_set_stack_position_no_sync: assertion 'window->stack_position
>= 0' failed
- Invalid window geometry for xdg_surface@24. Ignoring for now, but this will
result in client termination in the future.
- GNOME Shell crashed with signal 8
- (EE) failed to read Wayland events: Broken pipe
- Lost connection to Wayland compositor.
+ meta_window_set_stack_position_no_sync: assertion 'window->stack_position
>= 0' failed
+ Invalid window geometry for xdg_surface@24. Ignoring for now, but this will
result in client termination in the future.
+ GNOME Shell crashed with signal 8
+ (EE) failed to read Wayland events: Broken pipe
+ Lost connection to Wayland compositor.
This suggests that a client with invalid geometry is able to put Mutter
/ GNOME Shell into an inconsistent window stacking state and crash the
compositor. Regardless of whether the client behaves perfectly, the
compositor should not crash from this situation.
Steps to reproduce:
1. Log into the default Ubuntu 25.10 GNOME Wayland session
(XDG_SESSION_TYPE=wayland).
2. Run a Wayland client that creates a normal toplevel window and
(apparently) ends up with invalid window geometry under xdg-shell.
3. Observe GNOME Shell crash and restart.
4. Check the system journal and see the “Invalid window geometry for
xdg_surface” message followed by the stack position assertion and “GNOME Shell
crashed with signal 8”.
Additional information:
- The same Wayland client did not cause any GNOME Shell crashes on Ubuntu
25.04 (also using a GNOME Wayland session) on the same machine, so this appears
to be a regression in Ubuntu 25.10 / the newer GNOME Shell/Mutter stack.
- The crash is reproducible even with all GNOME Shell extensions disabled.
- The system is up to date with all Ubuntu 25.10 updates installed.
From a desktop stability perspective, it would be helpful if Mutter
handled this invalid-geometry situation without hitting the
stack_position assertion and crashing the whole session.
+ https://errors.ubuntu.com/oops/9b8baec3-bf9e-11f0-a84a-fa163ec8ca8c
+
ProblemType: Bug
DistroRelease: Ubuntu 25.10
Package: gnome-shell 49.0-1ubuntu1
ProcVersionSignature: Ubuntu 6.17.0-6.6-generic 6.17.1
Uname: Linux 6.17.0-6-generic x86_64
ApportVersion: 2.33.1-0ubuntu3
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: ubuntu:GNOME
Date: Sun Nov 9 08:10:22 2025
DisplayManager: gdm3
InstallationDate: Installed on 2025-02-04 (277 days ago)
InstallationMedia: Ubuntu 24.10 "Oracular Oriole" - Release amd64 (20241009.4)
ProcEnviron:
- LANG=zh_CN.UTF-8
- PATH=(custom, no user)
- SHELL=/bin/bash
- TERM=xterm-256color
- XDG_RUNTIME_DIR=<set>
+ LANG=zh_CN.UTF-8
+ PATH=(custom, no user)
+ SHELL=/bin/bash
+ TERM=xterm-256color
+ XDG_RUNTIME_DIR=<set>
RelatedPackageVersions: mutter-common 49.0-2ubuntu5
SourcePackage: gnome-shell
UpgradeStatus: Upgraded to questing on 2025-11-08 (0 days ago)
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Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2130963
Title:
GNOME Shell crashes when a Wayland client triggers “Invalid window
geometry for xdg_surface” and a stack position assertion failure.
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https://bugs.launchpad.net/mutter/+bug/2130963/+subscriptions
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