After updating Qt to 5.15.8 (testing, ~amd64) on my Gentoo system running KDE Plasma 5.26.5 (~amd64), I'm dealing with a bunch of issues with the desktop:

  • All launchers are broken, appearing as blank files. If I click on any launcher, I get an toast notification from Plasma Workspace with the error "Unknown application folder".
  • The desktop itself shows the following error message:

    The file or folder $HOME/Desktop does not exist.

  • The Application Launcher menu is completely empty.
  • All file associations are missing. If I open Dolphin via KRunner (minimizing all windows and typing while on the desktop) and try to open any file, I get an empty list of applications, regardless of file type.

Rolling back the Qt update to 5.15.7 (stable, amd64) did not help. The desktop was running during the update, so something likely got corrupted during the update process.

I do have a Snapper snapshot of the system from eight days ago, so I'm wondering if there's there some specific configuration file that got corrupted which I could restore to recover from this condition. Otherwise, where does the problem lie? I really don't want to erase my whole Plasma configuration.

Edit: The same issues are visible on a completely new user account, so the issue is with KDE itself.

Edit 2: A rebuild of Qt and KDE packages did not help.

Edit 3: Reverting the system (but not /home) to the last snapshot fixed the desktop error message, but not the broken launchers. Deleting all qmlcache folders in .cache did not help.

Edit 4: The dev-qt/* and kde*/* packages are built with the LLVM/Clang 15 toolset.

Most of the issues are visible in the screenshot below.

Broken KDE Plasma desktop

  • 1/ "running KDE Plasma 5.26" You mean unstable 5.26.5 ? 2/ after updating Qt You mean from 5.15.7 to unstable 5.15.8 ?
    – MC68020
    Jan 9, 2023 at 4:16
  • Yes, edited the question to clarify.
    – bwDraco
    Jan 9, 2023 at 4:25
  • Did you try wiping the .cache directory ? After whatever qt update I systematically delete all qmlcache entries.
    – MC68020
    Jan 9, 2023 at 4:45

2 Answers 2


Exact same problem here on Gentoo, I also have everything compiled with clang (no LTO however). For me this happend after the update to Qt to 5.15.8 as well, however I'm not sure if this problem manifested earlier and updating dev-qt invalidated the cache which made this issue visible.

This problem still persists with using dev-qt/*-5.15.8-9999 versions from qt and kde-frameworks-5-live, kde-gear-live and kde-plasma-live sets from kde overlay.

Also cleaned all qt and kde configuration files found in ~/.config, ~/.cache and ~/.local/share/.

I did file a bug here https://bugs.kde.org/show_bug.cgi?id=464140, however I'm not sure if this is the right place, or if kservice is really the problem.

Edit 1: Forcing a rebuild with gcc of dev-qt/*, kde-frameworks/*, kde-plasma/* and kde-apps fixed the issue (at least for the git versions).

Edit 2: Rebuilt ~amd64 packages with gcc and it works as well, so the culprit seems to be clang-15.0.6

Edit 3: The same issue occurs when using clang with -O2. Aggressive compiler flags being the issue can be ruled out. However I could boil the problem down to dev-qt/*, compiling this category with gcc should be enough.

  • Thanks, I'll switch the dev-qt/* and kde*/* packages back to GCC and try again.
    – bwDraco
    Jan 12, 2023 at 20:53
  • And looks like using GCC did the trick. Thanks!
    – bwDraco
    Jan 14, 2023 at 4:43

I ended up having to roll back the system to the last snapshot (excluding /home, some configuration and log files, and kernels and modules), delete all the .kcache files and qmlcache folders in ~/.cache, and bring the system up-to-date again.

I'm not sure what went wrong, but I suspect the KDE packages don't play nice with the latest Qt packages. While I haven't had issues with the testing (~amd64) KDE packages (and I have kde*/* ~amd64 in package.accept_keywords), I'll be sticking with stable Qt for the time being (at least until the next KDE update).

Edit: I tried the Qt update again without the X server running and got the same problem. Ended up rolling it back 🙁

  • Having followed for >10 years the qt* & kde* packages stabilization requests under gentoo-bugzilla discouraged me very soon to run qt* & kde-plasma & kde-frameworks tildarched… :-) Anyway… Since qt*5* updates are provided by the KDE team and generally distributed before a kde-plasma & framework & apps release update, I would strongly advise not to run qt* stable and kde-plasma & framework tildarched.
    – MC68020
    Jan 10, 2023 at 11:46
  • Updated my answer. FWIW I have Qt and KDE packages built with Clang, the latter with full LTO.
    – bwDraco
    Jan 10, 2023 at 12:04

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