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.
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.
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.
A few things to check for the ‘No KScreen backend found’ error in Plasma 6 / Kubuntu:
- Check your session type and the backend plugin directory:
-
- echo $XDG_SESSION_TYPE
- ls -la /usr/lib/*/qt6/plugins/kf6/kscreen/
-
- 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.
- Reinstall the KScreen / KF6 screen backend packages:
-
- sudo apt update
- sudo apt install --reinstall libkf6screen8 libkf6screenbin8 libkscreen-bin kscreen plasma-workspace
-
- During distribution or release upgrades, backend libraries or plugin paths sometimes fail to transition cleanly to the Qt6/KF6 directories.
- Check environment variables:
- 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.
- Check the systemd unit logs for KScreen:
-
- journalctl --user -u plasma-kscreen.service -b
-
- This should show the exact error message or missing shared library causing the backend to fail to load on startup.
$journalctl --user -u plasma-kscreen.service -b
– No entries –
$ printenv | grep KSCREEN
KSCREEN_LOGGING=1
So, no entries for that.
After a long debugging session with Google Gemini (and several reboots), I could finally fix the misconfiguration issue.
First I wiped the kwin local config:
rm -f ~/.config/kwinoutputconfig.json
Then restarted Plasma:
systemctl --user restart plasma-kded.service
Then I killed all kscreen and kwin processes:
pkill -9 -f kscreen
pkill -9 -f kwin
And tried to run:
kscreen-doctor -o
It still hanged. The next question on the queue was my graphics card. I told Google that I was using an AMD laptop (and not nVidia or Intel graphics card), Google recommended me to run this command:
LD_LIBRARY_PATH=/usr/lib/x86_64-linux-gnu kscreen-doctor -o
And it finally showed the full configuration instead of freezing. To make the environment permanent, I needed to append the following line to my /etc/environment file:
LD_LIBRARY_PATH="/usr/lib/x86_64-linux-gnu"
Then I ran:
sudo update-initramfs -u
One last reboot later, I checked the command and it worked!
[19::21:47.148] unknown: adding output 63
[19::21:47.148] unknown: adding output 64
[19::21:47.149] unknown: Loading Wayland backend.
Output: 1 (REDACTED)
enabled
connected
priority 1
Panel
replication source:0
...
Then I loaded System Settings, went to the Display Configuration, and IT WORKED! Hurray!
So yeah, I think the misconfiguration happened during a botched Kubuntu 26.04 update.
