Created attachment 187440 [details] Visual demonstration of the issue. SUMMARY After the very latest KDE neon updates I did (December 2025), I had lot of troubles with KDE under Wayland, and one of the issue I'm reporting today: window thumbnails preview in the task manager are completely black on Wayland and the whole Plasma session crashes very frequently. X11 session is now completely unusable due to massive graphical artifacts and corruption so I can't check if it works here. STEPS TO REPRODUCE 1. Be me on my computer 2. Update KDE neon to the latest packages available in December 2025 3. Log in to a Plasma (Wayland) session 4. Open a few applications 5. Hover over any task manager entry OBSERVED RESULT - Thumbnails/previews are solid black (no window content visible at all) - Plasma/KWin crashes several times per hour, often with full session freeze or automatic restart of plasmashell/KWin, even when doing unrelated things - Switching to Plasma (X11) session: severe graphical glitches, heavy artifacts, flickering, missing or corrupted UI elements everywhere – session became practically unusable after this same update EXPECTED RESULT - Correct live thumbnails showing the actual window content - Stable Wayland and X11 sessions without crashes or graphical corruption SOFTWARE/OS VERSIONS Windows: macOS: Linux/KDE Plasma: KDE neon User Edition (fully updated as of 8 December 2025) KDE Plasma Version: 6.5.3 KDE Frameworks Version: 6.20.0 Qt Version: 6.10.1 Kernel Version: 6.14.0-36-generic (64-bit) Graphics Platform: Wayland (black thumbnails + frequent crashes) / X11 (massive artifacts) Processors: 20 × 13th Gen Intel® Core™ i7-13700H Memory: 32 Gio of RAM (31.0 Gio usable) Graphics Processor 1: NVIDIA GeForce RTX 4060 Laptop GPU (driver 570.195.03) Graphics Processor 2: Intel® Iris® Xe Graphics ADDITIONAL INFORMATION All problems started immediately after the last KDE neon update cycle I did.
Sorry this is happening, but we need one issue per bug report, please. Would you like to use this bug report to report the KWin crashes, or the black thumbnails?
(In reply to Nate Graham from comment #1) > Sorry this is happening, but we need one issue per bug report, please. Would > you like to use this bug report to report the KWin crashes, or the black > thumbnails? Yes sorry, I actually wanted to report the black thumbnails, the crash info was just for more context. Thanks in advance for your help!
All right, black thumbnails issue here. Do you see the same black thumbnails in other places too, like the Overview effect (invoked with Meta+W) or the screen sharing window chooser dialog (invokable using OBS)?
(In reply to Nate Graham from comment #3) > All right, black thumbnails issue here. > > Do you see the same black thumbnails in other places too, like the Overview > effect (invoked with Meta+W) or the screen sharing window chooser dialog > (invokable using OBS)? In the "Overview effect" (Meta+W) I see the previews, but in the screen sharing window chooser dialog I also see black thumbnails...
*** Bug 513142 has been marked as a duplicate of this bug. ***
I don't have an NVIDIA GPU myself so I can't verify this, but I asked two KDE developers who do, and neither could reproduce the issues with their hardware running current git master of Pipewire and other KDE stuff.
Journal logs may be more revealing — with a driver issue, I expect to see the Nvidia driver practically screaming. Could you take a note of the time before logging in, then log in, attempt to show a Task Manager thumbnail, and then note the time and log out? With these times, you can extract the logs with the command: journalctl --since "14:00:00" --until "16:00:00" > logs.txt which will create a file 'logs.txt' in your current directory and attach them to this bug report? You could do this from a TTY after the session, or during if it is not too unstable.
(In reply to Oliver Beard from comment #7) > Journal logs may be more revealing — with a driver issue, I expect to see > the Nvidia driver practically screaming. > > Could you take a note of the time before logging in, then log in, attempt to > show a Task Manager thumbnail, and then note the time and log out? > > With these times, you can extract the logs with the command: > > journalctl --since "14:00:00" --until "16:00:00" > logs.txt > > which will create a file 'logs.txt' in your current directory and attach > them to this bug report? You could do this from a TTY after the session, or > during if it is not too unstable. I will try that and come back here to give you the results. Other than that, is there anything I can do to try to fix it? Like reinstalling a package or something, because it may be corrupted since I had a lot of trouble installing the last update and I had to reinstall some other packages after it (for example, some of my applets were still there but not recognized, so I had to install the packages again for them to work again).
(In reply to NitramO from comment #8) > (In reply to Oliver Beard from comment #7) > > Journal logs may be more revealing — with a driver issue, I expect to see > > the Nvidia driver practically screaming. > > > > Could you take a note of the time before logging in, then log in, attempt to > > show a Task Manager thumbnail, and then note the time and log out? > > > > With these times, you can extract the logs with the command: > > > > journalctl --since "14:00:00" --until "16:00:00" > logs.txt > > > > which will create a file 'logs.txt' in your current directory and attach > > them to this bug report? You could do this from a TTY after the session, or > > during if it is not too unstable. > > I will try that and come back here to give you the results. > > Other than that, is there anything I can do to try to fix it? Like > reinstalling a package or something, because it may be corrupted since I had > a lot of trouble installing the last update and I had to reinstall some > other packages after it (for example, some of my applets were still there > but not recognized, so I had to install the packages again for them to work > again). Part 1: https://pastebin.com/raw/2rZKvkf6 Part 2: https://pastebin.com/raw/C8X9na5j Good luck... 🙃
(In reply to NitramO from comment #9) > (In reply to NitramO from comment #8) > > (In reply to Oliver Beard from comment #7) > > > Journal logs may be more revealing — with a driver issue, I expect to see > > > the Nvidia driver practically screaming. > > > > > > Could you take a note of the time before logging in, then log in, attempt to > > > show a Task Manager thumbnail, and then note the time and log out? > > > > > > With these times, you can extract the logs with the command: > > > > > > journalctl --since "14:00:00" --until "16:00:00" > logs.txt > > > > > > which will create a file 'logs.txt' in your current directory and attach > > > them to this bug report? You could do this from a TTY after the session, or > > > during if it is not too unstable. > > > > I will try that and come back here to give you the results. > > > > Other than that, is there anything I can do to try to fix it? Like > > reinstalling a package or something, because it may be corrupted since I had > > a lot of trouble installing the last update and I had to reinstall some > > other packages after it (for example, some of my applets were still there > > but not recognized, so I had to install the packages again for them to work > > again). > > Part 1: https://pastebin.com/raw/2rZKvkf6 > > Part 2: https://pastebin.com/raw/C8X9na5j > > Good luck... 🙃 UPDATE: Root Cause Identified and Fixed! After extensive debugging, I found the root cause of this issue. CAUSE: The environment variable __NV_PRIME_RENDER_OFFLOAD=1 was set globally via: ~/.config/environment.d/90-nvidia.conf This file contained a single line: __NV_PRIME_RENDER_OFFLOAD=1 This variable forces all applications to render on the NVIDIA dGPU. On hybrid GPU laptops running Wayland, this breaks buffer sharing between the iGPU (used by KWin compositor for display) and the dGPU (forced for all app rendering). The Task Manager thumbnails fail to capture window content properly, resulting in black previews. The Overview effect (Meta+W) still works because it uses a different capture method. HOW THIS FILE APPEARED: When I reported this bug, I mentioned that it appeared after a KDE update. However, around the same time, I also updated my NVIDIA drivers from version 570 to the latest 580-open (which was marked as recommended). The 90-nvidia.conf file was most likely auto-generated during this NVIDIA driver update, not by the KDE update itself. This explains why I initially associated the bug with the KDE update, as both updates happened simultaneously. I was not aware of this file's existence until investigating this bug. SOLUTION: 1. Remove or rename the file: mv ~/.config/environment.d/90-nvidia.conf ~/.config/environment.d/90-nvidia.conf.bak 2. Clear GPU caches: rm -rf ~/.nv rm -rf ~/.cache/nvidia rm -rf ~/.cache/mesa_shader_cache rm -rf ~/.cache/mesa_shader_cache_db rm -rf ~/.cache/qtshadercache* 3. Log out and log back in (or reboot) RESULT: After applying this fix, window thumbnails in the Task Manager are now displaying correctly. Updated system info: - Operating System: KDE neon User Edition - KDE Plasma Version: 6.5.4 - KDE Frameworks Version: 6.21.0 - Qt Version: 6.10.1 - Kernel Version: 6.14.0-37-generic (64-bit) - Graphics Platform: Wayland - Graphics Processor 1: NVIDIA GeForce RTX 4060 Laptop GPU (driver 580-open) - Graphics Processor 2: Intel Iris Xe Graphics - Memory: 32 GB RAM