SUMMARY The wallpaper on a secondary monitor will disappear on reboot/power off, leaving a black background. It can be restored in "System Settings" by temporarily making the secondary monitor the primary. STEPS TO REPRODUCE 1. Have a system with multiple monitors. 2. Have a wallpaper in the background on each monitor 3. Restart system several times, perhaps powering off. OBSERVED RESULT The monitor that is the secondary monitor will have a black background. The wallpaper can be restored by making the secondary monitor the primary, pressing "Apply." EXPECTED RESULT Both monitors should retain their backgrounds to the previously set values on restart/power off. SOFTWARE/OS VERSIONS Windows: macOS: Linux/KDE Plasma: (available in About System) KDE Plasma Version: KDE Frameworks Version: Qt Version: ADDITIONAL INFORMATION
What kind of GPU are you using?
It's an Nvidia GTX 1050 Ti. I would be surprised if it's a hardware problem. Seems to me like a problem with the "restore the wallpaper on the secondary monitor(s) code."
In this case I think it's actually not a hardware issue. :) Some AMD GPUs trigger a kernel bug that causes issues like this, but NVIDIA GPUs don't have the same problem. It is more likely to be a software issue on our side. If you right-click on the black background, do you see a context menu? Can you move desktop icons there? Was there a panel there too that inappropriately moved elsewhere
Right clicking does NOT bring up a context menu. I can move icons over to the black background, but they aren't visible there. Interestingly, I don't think there were any icons on either screen initially, but they appeared later, when I right clicked on the wallpaper. I don't believe there were ever any panels on that monitor.
Ah oh, so it's not just that the wallpaper went missing--the whole containment is missing. Can you check in the Display Configuration KCM whether or not one of your screens is slightly overlapping the other one--even by just one pixel? If so, this is Bug 391531.
I have used KDE for a long time but I'm not too familiar with the internals. I used the Nvidia X Server settings to identify positions. The monitors are 1680 x 1050. The secondary monitor is at 0,0. The primary is at 1680, 0. That doesn't seem to be an overlap. I don't know how to get into the KCM settings you asked for. I hope this answers your question.
Thanks for the info. If there's no overlay, then this is in fact Bug 371717. *** This bug has been marked as a duplicate of bug 371717 ***
*overlap
*** This bug has been marked as a duplicate of bug 442826 ***
*** This bug has been marked as a duplicate of bug 353975 ***