Plasma flickers / black screen on X11 after linux-image-6.8.0-142-lowlatency + NVIDIA 580 (GTX 1050) — XFCE is stable

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Ubuntu Version

Ubuntu 24.04 LTS

Desktop Environment (if applicable)

KDE Plasma

Problem Description

After yesterday’s kernel update, Plasma on X11:
desktop appears, then flickers and vanishes
black screen with only the mouse, or panel/icons not clickable (plasmashell / KWin)
SDDM login screen is fine; freeze starts after password when Plasma starts
nvidia-smi shows Xorg + kwin_x11 running while the session is already unusable
Same machine on XFCE with the same kernel and the same 580 driver: no flicker.
Konsole (KDE) later died with SIGSEGV (11); xfce4-terminal does not.
What we already did
Switched SATA mode to AHCI earlier (unrelated; disks are fine)
Forced AHCI/NVIDIA modules via update-initramfs on 138 vs 142
Mixed 535 + 580 packages; Ubuntu kept pulling 580 as recommended (ubuntu-drivers lists 580)
apt-mark hold on 580 then blocked installing 470-server until unhold + purge
Disabled KWin compositing (kwinrc) — stop flicker but dead panel/clicks
Disabled xfwm4 compositing — minimize freeze on XFCE improved
Forced X11 in SDDM; ~/.dmrc Session=xfce
Did not want to stay on 138 forever; 142 + NVIDIA 580 works if the DE is XFCE, not Plasma
uname -r / nvidia-smi on the working XFCE session:
text6.8.0-142-lowlatency
NVIDIA-SMI 580.178.04 Driver Version: 580.178.04 CUDA Version: 13.0
GPU 0 GeForce GTX 1050 Disp.A On
Processes: Xorg, xfwm4, firefox
Question
Is this a known regression of 6.8.0-142-lowlatency + nvidia-580 + KWin/Plasma on Pascal (GTX 1050)?
What is the supported combination on 24.04 for this GPU: stay on 535, stay on 138, file a kernel/linux-modules-nvidia-580 bug, or is Plasma X11 on 580 simply unsupported on this card now?
Workaround we can live with: XFCE + 142 + 580. We would rather have Plasma back without pinning an old kernel.

Relevant System Information

Ubuntu: 24.04.5 LTS
Kernel (broken with Plasma): 6.8.0-142-lowlatency
Kernel that previously worked with Plasma: 6.8.0-138-lowlatency
GPU: NVIDIA GeForce GTX 1050 (2 GB)
Driver now: proprietary 580.178.04 (nvidia-smi OK, CUDA 13.0)
Also tested: nvidia-driver-535, nvidia-driver-470 / 470-server
Display manager: SDDM
Session: Plasma X11 flickers/crashes; Plasma Wayland also bad; Xfce Session + xfwm4 is usable on the same 142 + 580 stack

2

If something breaks after a package upgrade file a bug, please. If you suspect the (lowlatency) kernel:

$ ubuntu-bug linux-lowlatency

It might also be worthwhile to check Launchpad for newly filed bugs to see if someone else reported it already. Granted that’s a pain since a bug can be reported against any of our many kernels and there’s no easy way to search through all of them. One way is to look at our mailing list archive. We have a bot that searches daily for new kernel bugs and sends a summary email to the mailing list. For example: The Daily Bug Report for 2026-09-23 23:00:01.719199+00:00

3 Likes
3

Update 2026-09-26:

Plasma X11 is stable now on the same stack:

  • 6.8.0-142-lowlatency
  • NVIDIA 580.178.04 (GTX 1050)

No new Plasma/KWin/NVIDIA packages. What changed yesterday (apt upgrade):

xserver-xorg-core 2:21.1.12-1ubuntu1.6 → 2:21.1.12-1ubuntu1.8
(also xserver-common, xserver-xorg-legacy, xserver-xephyr)

Likely an Xorg fix interacting with KWin + proprietary NVIDIA.

I still have XFCE as fallback. Will test suspend/resume.