[Desktop] KDE Plasma started crashing

[troymcclure]

Hello,

I am using Kubuntu 26.04 LTS and I am experiencing repeated KDE Plasma crashes.

The issue occurs even on a freshly formatted and newly installed Kubuntu 26.04 system, with no previous configuration or older installation carried over.

• Session: Wayland
• Plasma crashes unexpectedly, even when the system is idle.
• Multiple notifications appear stating that plasmashell has crashed unexpectedly.
• The system generates DrKonqi/systemd-coredump crash reports.
• There are also messages related to fontconfig.
• I ran fc-cache, which completed successfully with fc-cache: succeeded.
• After rebooting, the problem may temporarily disappear, but plasmashell eventually crashes again spontaneously.
• An X11 session is also available (/usr/share/xsessions/plasmax11.desktop), although I am currently using Wayland.

Since the same problem occurs immediately after a clean installation, it does not appear to be caused by an old user configuration or a previously installed system.

The issue seems to have appeared after a recent update and may be related to Plasma, Wayland, or fontconfig.

I can provide journalctl logs, system information, and DrKonqi crash reports if needed.

Thank you.

[claydoh]

There are also messages related to fontconfig.

Are you using Google Chrome? Not anything Chromium-based, just Chrome. *Maybe* Edge.

If so look here for some links and repair methods.

https://www.reddit.com/r/Kubuntu/com...rome_corrupts/

There is a bug in Chrome and/or fontconfig that seems to affect some of us, maybe specific to Plasma 6.6?

I have had no issue myself, but a number of people have been reporting similar problems since the last Chrome update.

[troymcclure]

Are you using Google Chrome? Not anything Chromium-based, just Chrome.

If so look here for some links and repair methods.

https://www.reddit.com/r/Kubuntu/com...rome_corrupts/

There is a bug in Chrome that seems to affect some of us, maybe specific to Plasma 6.6?

I have had no issue myself, but a number of people have been reporting similar problems since the last Chrome update.

No, I don't use Google Chrome at all.

I only use Microsoft Edge, Firefox, and Brave. I don't have Google Chrome installed.

Also, as I mentioned in my previous post, the problem occurs even after a clean installation of Kubuntu 26.04.

So I don't think the Chrome-specific issue applies to my case.

[troymcclure]

Until yesterday morning, everything was working normally. After the recent updates, the problem started occurring, with Plasma repeatedly crashing.

I have already formatted and reinstalled Kubuntu three times, and the same problem occurs even on a clean installation.

At this point, the problem is preventing me from working normally. Since it started immediately after the recent updates and persists after multiple clean installations, I suspect that something introduced by one of the recent updates may be causing the issue.

Any help identifying the specific package or recent change responsible would be greatly appreciated.

[claydoh]

Still, as font cache corruption seems to be the cause for the crashes in the past couple of days, it is still worth trying the repair, if nothing other than to eliminate this.


You can see what was updated last by looking at /var/log/apt/history.log. Look at the bottom of the file for the moist current updates.

Also some basic system specs, particularly graphics, will be helpful.

[troymcclure]

I found that this appears to be a known issue related to fontconfig and Qt 6.10.

The relevant Ubuntu bugs are:

• LP #2168311 – fonts-katex/fontconfig can cause Plasma to fail to start.
• LP #2168420 – Qt6 applications such as plasmashell can crash with SIGSEGV in FcCharSetHasChar().
• LP #2168504 – Qt 6.10 does not properly handle a fontconfig structure without a charset; an upstream fix exists but has not yet been included in Ubuntu/Kubuntu 26.04.

This also explains why clearing the font cache temporarily restored Plasma on my system, but the crashes returned later.

[claydoh]

It seems to be that the Chrome update to version 154, it uses a built-in fontconfig version newer (2.18.1) than what Ubuntu and Fedora use (2.17.1), which is the ultimate cause, for those affected by this after the Chrome update this past week.

Otherwise, there have not been any updates to Qt or fontconfig in 26.04 since well before 26.04.1, or even since April (fontconfig) and I can't tell what might be causing it for those not using Chrome.

[troymcclure]

I'm sharing the solution I found.

https://dev.to/zerolock/kde-plasma-c...ition-fix-2ebm

[skyfishgoo]

that seems like a lot more work than just not using a chromium based browser until this gets fixed.

[troymcclure]

that seems like a lot more work than just not using a chromium based browser until this gets fixed.

It is no longer just an issue with Chrome. Clean installations were performed without installing anything else, yet the error appeared after updating. While Chrome was known to be involved, it is not the sole cause.

[skyfishgoo]

the brave browser is chromium based

[claydoh]

And PWA/Electron things like Telegram, among others might be involved as well.

[Cincinnatus]

Mine is crashing as well and it's not a fresh install. It happened after I logged out and tried to log back in. Just been flashing with the crash message showing. Mine crashes immediately after signing in to my main admin account.

I'm not sure how to run any conmands or anything because I can't even click on the app menu.

Brave browser is my default browser and if I click on the "learn more" link in the crash message it opens Brave just fine and even lets me use it. Doesn't even flicker.

Meanwhile in the background my desktop is steadily flashing and doesn't let me do anything

Also, I just realized that if I sign into a different user account that one seems to work fine (possibly because I haven't updated anything on it yet?) It's only my main user account

[claydoh]

I'm not sure how to run any conmands or anything because I can't even click on the app menu.

ctrl-alt-f3, f4, etc gets you to a tty

Also, I just realized that if I sign into a different user account that one seems to work fine (possibly because I haven't updated anything on it yet?) It's only my main user account

Yes, that is why.

Chrome just updated today to fix their booboo, Chromium either has or will soon, so Brave should not be too far behind.

[Cincinnatus]

I'm not very computer savy but in case anyone else was stuck like I was...

I logged into the account with the plasma shell crashing and hit Ctrl-alt-T then put the fc-cache -r command in and that solved my issue