Problems with KDE Plasma 6 on Debian Trixie

I’m a big Debian fan and I’m currently running Debian 13, aka, “Trixie” on my main laptop workstation. Currently Trixie is Debian’s “testing” branch. Despite being a test version, Trixie has generally proven very stable and reliable. And we users get all the new stuff very promptly. I’m also rather keen on the KDE desktop, despite some of its irritating teething problems whenever a new version is released. That was until KDE Plasma 6 came along.

Editor’s note, 2025-07-25: Debian Bookworm (v12) users running KDE Plasma desktop will likely encounter this issue when upgrading to Debian Trixie (v13). The upgrade automatically upgrades Plasma 5 to Plasma 6. In all the KDE-based Bookworm -> Trixie upgrades we have undertaken thus far, the following fix works perfectly. We would be very interested to learn if works for you?

Problems

Unfortunately, with a “testing” version of an operating system, things can sometimes go wrong. As just happened when Debian pushed KDE Plasma 5 to Plasma 6 upgrade on its “testing” branch users. In my case, it occurred during a normal routine upgrade. As a consequence, three seemingly nasty problems arose that made KDE Plasma 6 almost unusable. for a few hours, while I figured out a fix..

Application launcher (aka “start menu”) is completely empty. No applications in any app launcher. Didn’t matter which application launcher ‘alternative’ I tried. Also I note that “Edit Applications” does nothing.
Open applications do not appear on task bar.

Cannot take screen capture with spectacle, following error returned:-

An error occurred while taking a screenshot.
KWin screenshot request failed:
The process is not authorized to take a screenshot
Potentially relevant information:
   Method: CaptureScreen
   Method specific arguments: “eDP-1”

Solution

Fortunately, seems all three issues are related to the same root cause. I solved all three issues by simply reinstalling xdg-desktop-portal-kde then restarting the desktop session.

sudo apt install --reinstall xdg-desktop-portal-kde

I have to admit that xdg-desktop-portal is something of a dark-art as far as I am concerned. One does not normally fix GNU/Linux problems by reinstalling stuff. Nevertheless, this quick and dirty bodge made my computer usable again. In fact, Plasma 6 on Debian 13 seems remarkably smooth and pleasant now.

I hope this helps someone. 🙂