Error in Display Configuration (System Settings): "No KScreen backend found."

Help
1

I can’t remember when this message started appearing whenever I tried to configure my screen, I think it was after upgrading my version of Kubuntu (I’ve upgraded more than once, the last one was for 26.04).

I’m using an HP laptop with external monitor in a dual-monitor configuration. I used to configure the monitor and desktop and arrange the desktops, but now I can’t even see any info.

The screen gives a message in red that says: “No KScreen backend found. Please check your KScreen installation.” I tried reinstalling KScreen and even kubuntu-desktop, but the error keeps appearing.

Help appreciated.

bug_kde_kscreen
bug_kde_kscreen1319×738 85 KB

2

no kscreen backend usually means the plugin dir got wrecked after the upgrade for me

id try:
-echo $XDG_SESSION_TYPE
-ls /usr/lib/*/qt6/plugins/kf6/kscreen/
-sudo apt install --reinstall libkscreen-bin libkf6screen8 libkf6screenbin8 plasma-workspace
-log out/in once

if the ls comes back empty, the kscreen backend packages never landed on this install. also unset KSCREEN_BACKEND if u ever exported it.

3

Sorry for the delay.

$ echo $XDG_SESSION_TYPE
wayland

$ ls /usr/lib/*/qt6/plugins/kf6/kscreen/
KSC_Fake.so KSC_KWayland.so KSC_XRandR.so

About libkf6screenbin8, there’s no such package. I also looked for it in Synaptic and it’s not there. I tried reinstalling the other packages. Rebooted, still no dice.

4

A few things to check for the ‘No KScreen backend found’ error in Plasma 6 / Kubuntu:

  1. Check your session type and the backend plugin directory:
  3. echo $XDG_SESSION_TYPE
  4. ls -la /usr/lib/*/qt6/plugins/kf6/kscreen/
  6. Under Wayland, Plasma uses KSCNXwayland.so, and under X11 it uses KSCN_XRandR.so. If that directory is missing or empty, System Settings cannot communicate with any display backend.
  7. Reinstall the KScreen / KF6 screen backend packages:
  9. sudo apt update
  10. sudo apt install --reinstall libkf6screen8 libkf6screenbin8 libkscreen-bin kscreen plasma-workspace
  12. During distribution or release upgrades, backend libraries or plugin paths sometimes fail to transition cleanly to the Qt6/KF6 directories.
  13. Check environment variables:
  14. Run printenv | grep KSCREEN to see if KSCREEN_BACKEND was manually set in /etc/environment or your shell configuration. Remove or unset it if present so KScreen can autodetect the correct backend.
  15. Check the systemd unit logs for KScreen:
  17. journalctl --user -u plasma-kscreen.service -b
  19. This should show the exact error message or missing shared library causing the backend to fail to load on startup.
5

$journalctl --user -u plasma-kscreen.service -b
– No entries –

$ printenv | grep KSCREEN
KSCREEN_LOGGING=1

So, no entries for that.