Public bug reported:
System release version:
Description: Ubuntu 26.04 LTS
Release: 26.04
Package Version Policies:
kscreen:
Installed: 4:6.6.4-0ubuntu1
Candidate: 4:6.6.4-0ubuntu1
Version table:
*** 4:6.6.4-0ubuntu1 500
500 http://us.archive.ubuntu.com/ubuntu resolute/universe amd64 Packages
100 /var/lib/dpkg/status
libkscreen-bin:
Installed: 4:6.6.4-0ubuntu1
Candidate: 4:6.6.4-0ubuntu1
Version table:
*** 4:6.6.4-0ubuntu1 500
500 http://us.archive.ubuntu.com/ubuntu resolute/universe amd64 Packages
100 /var/lib/dpkg/status
libkscreen-data:
Installed: 4:6.6.4-0ubuntu1
Candidate: 4:6.6.4-0ubuntu1
Version table:
*** 4:6.6.4-0ubuntu1 500
500 http://us.archive.ubuntu.com/ubuntu resolute/universe amd64 Packages
500 http://us.archive.ubuntu.com/ubuntu resolute/universe i386 Packages
100 /var/lib/dpkg/status
libkf6screen8:
Installed: 4:6.6.4-0ubuntu1
Candidate: 4:6.6.4-0ubuntu1
Version table:
*** 4:6.6.4-0ubuntu1 500
500 http://us.archive.ubuntu.com/ubuntu resolute/universe amd64 Packages
100 /var/lib/dpkg/status
kwin-wayland:
Installed: 4:6.6.4-0ubuntu1
Candidate: 4:6.6.4-0ubuntu1
Version table:
*** 4:6.6.4-0ubuntu1 500
500 http://us.archive.ubuntu.com/ubuntu resolute/universe amd64 Packages
100 /var/lib/dpkg/status
When did this start:
- After I upgraded from Kubuntu 25.10 to Kubuntu 26.04
What I expect to happen:
- The system menu to load the display settings.
What happens instead:
- System menu shows red error alert with the text "No KScreen backend found.
Please check your KScreen installation."
What I've tried/checked:
- Reinstalling kscreen
- Regenerating ~/.config/kwinoutputconfig.json
- Running with KSCREEN_BACKEND_INPROCESS=1
- Cleared my ~/.cache and ~/.config
- Create a new system user
- Disabling bluedevil (An arch thread found a bluedevil loading error
blocked the kscreen backend from loading)
- Found no missing shared library dependencies (ldd clean on all .so
files).
- Found backend plugins exist at /usr/lib/x86_64-linux-
gnu/qt6/plugins/kf6/kscreen/ (KSC_KWayland.so, KSC_XRandR.so,
KSC_Fake.so).
- kscreen-doctor --info finds all three KScreen backends. But defaulted
to XRandR. Creating /etc/xdg/kscreenrc with
PreferredBackend=KSC_KWayland fixed the selection, but did not resolve
the issue.
- kscreen-console returns empty config. kscreen-console json returns {}
after 1-2ms. kscreen-console outputs says "Config is invalid, probably
backend couldn't load." kscreen-console bug displays valid monitor data
but this is read from ~/.config/kwinoutputconfig.json, not from the live
backend.
- KWin is functioning correctly. kwin_wayland --version reports 6.6.4.
Information shows both outputs enabled with correct geometry. wayland-
info confirms kde_output_management_v2 (v19) and two
kde_output_device_v2 (v20) interfaces are advertised.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: kscreen 4:6.6.4-0ubuntu1
ProcVersionSignature: Ubuntu 7.0.0-15.15-generic 7.0.0
Uname: Linux 7.0.0-15-generic x86_64
ApportVersion: 2.34.0-0ubuntu2
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: KDE
Date: Sat May 16 11:09:41 2026
InstallationDate: Installed on 2024-05-27 (719 days ago)
InstallationMedia: Kubuntu 23.10 "Mantic Minotaur" - Release amd64 (20231010)
SourcePackage: kscreen
UpgradeStatus: Upgraded to resolute on 2026-05-15 (1 days ago)
** Affects: kscreen (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
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Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2152794
Title:
Opening the KDE displays system menu gives an error of "No KScreen
backend found."
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