I'm using KDE 5.59.0/Plasma 5.16.2 and while working, my screen flickered, after which it seemed the drop shadows from my windows were gone. I noticed because I have no borders around the windows and I had a few windows with some white content and they blended because there's no shadow or border.

I did not change any setting, and the shadows are still turned on in the System Settings. I tried changing the theme, reboot, install all latest updates, etc.

It seems not only the drop shadows work anymore, but the transparencies stopped working as well. I'm using the default Breeze theme and that should have rounded borders, but now they are square.

I can't figure out why the shadows/transparencies won't work, as I did not change any setting and did not do anything special, so any tips would be welcome.

1 Answer 1


OK, I figured it out: seems the 'Compositor' crashed. The Compositor can be found in the System Settings under Display and Monitor > Compositor.

There was a dialogue box there that said the Compositor had crashed. There was a button to re-enable Compositor startup. I had to reboot, after that everything was fine again!

Would be helpful if there was some sort of pop-up when a crash like this occurs, but now I know.

  • 1
    Nice find. Reenabling the OpenGL in the compositor fixed the issue.
    – R.J
    Apr 29, 2020 at 23:48
  • 1
    Oh, wow. This was driving me insane for months now and it even persisted over an OS update from 20.10 to 21.04 Also I think the whole OS experience is now much more performant again.
    – Max N
    May 2, 2021 at 22:23

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