Public bug reported:
In an Ubuntu 26.04 guest running Cinnamon (X11 session) under QEMU/KVM
with SPICE, the mouse pointer becomes misaligned after any change of
screen resolution. This happens both when switching from the LightDM
greeter to the user session (which use different resolutions) and when
changing the resolution inside a running session.
After the change, the pointer position the guest uses no longer matches
the position of the host cursor. The offset grows toward the bottom-
right of the screen, consistent with coordinates being scaled to the
previous resolution.
Environment
Guest: Ubuntu 26.04, Cinnamon, X11 session (XDG_SESSION_TYPE=x11)
spice-vdagent version: 0.23.0-1ubuntu0.1
Host: QEMU/KVM, SPICE display, mouse mode client
Video device: Virtio
Steps to reproduce
Log into a Cinnamon X11 session in a QEMU/KVM guest with SPICE and
spice-vdagent running.
Change the screen resolution, either from Display settings or by resizing the
viewer window with auto-resize enabled.
Move the mouse around the screen.
Expected result
The guest pointer follows the host cursor exactly at the new resolution.
Actual result
The guest pointer is scaled according to the previous resolution. xrandr
reports the correct current screen size, but spice-vdagent keeps
reporting the old one to spice-vdagentd.
Debug output (spice-vdagent -x -d, during a change from 1920x1200 to
1874x1078):
spice-vdagent: No guest output map, using output index as display id
spice-vdagent: Sending guest screen resolutions to vdagentd:
spice-vdagent: display_id=0 - 1874x1078+0+0
spice-vdagent: 0x651021003070 sent guest xorg resolution, arg1: 1920, arg2:
1200, size 20
The per-display geometry is correct (1874x1078), but the "guest xorg
resolution" sent to vdagentd is still 1920x1200. At that moment, xrandr
| head -1 reports current 1874 x 1078.
(The "failed to call GetCurrentState from mutter over DBUS" messages
also appear in the log. They are expected under Cinnamon, since
org.gnome.Mutter.DisplayConfig does not exist there, and seem
unrelated.)
Workarounds
sudo systemctl restart spice-vdagentd immediately fixes the alignment until the
next resolution change.
Restarting only the session agent (pkill -x spice-vdagent; spice-vdagent) also
fixes it. This suggests the stale value lives in the agent, not the daemon.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: spice-vdagent 0.23.0-1ubuntu0.1
ProcVersionSignature: Ubuntu 7.0.0-34.34-generic 7.0.14
Uname: Linux 7.0.0-34-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: X-Cinnamon
Date: Wed Sep 30 09:42:22 2026
InstallationDate: Installed on 2025-09-18 (377 days ago)
InstallationMedia: Xubuntu 24.04.3 LTS "Noble Numbat" - Release amd64
(20250805.1)
ProcEnviron:
LANG=it_IT.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
SourcePackage: spice-vdagent
UpgradeStatus: Upgraded to resolute on 2026-09-24 (6 days ago)
** Affects: spice-vdagent (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute
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https://bugs.launchpad.net/bugs/2168964
Title:
spice-vdagent keeps sending stale X screen size after resolution
change, causing mouse misalignment
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