Last week I updated a Kubuntu 26.04 LTS workstation and came back to a broken desktop. KDE Plasma would start, the desktop would flash for a second...
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I don't have the knowledge about you are explaining in this article. I'mt a noob user.
But in my case this happens to me after the update, but combinated with crhome v154 in Kubuntu 24.04
It's weird and i don't know how to explain it well, but i figure out this:
.. Ah and this not happens with chrome / chromium version 153 or don't open it
I hope this help to you
Thanks for sharing this. The Chrome v154 angle is interesting, it might be writing something to a shared config or font directory on first launch that triggers the same race condition at login. The fact that v153 works and v154 breaks is a useful clue. If you want to dig deeper, run coredumpctl info plasmashell after the crash and check if FcCharSetHasChar appears in the stack trace. That would tell you if it is the same root cause or something different.
i use arch btw 💀
Fair enough, you probably never see this kind of problem anyway.
You saved my day! Thanks!
This worked on this machine after upgrading and getting a crashing plasmashell:
OS: Kubuntu 26.04.1 LTS (Resolute Raccoon) x86_64
DE: KDE Plasma 6.6.6
GPU: Intel Graphics @ 2.50 GHz [Integrated]
CPU: Intel(R) Core(TM) Ultra 7 365 (8) @ 4.90 GHz
Theme: Breeze (Light) [Qt], Breeze [GTK2/3]
Kernel: Linux 7.0.0-34-generic
Host: 21V9S08K00 (ThinkPad X1 2-in-1 Gen 11)
Glad it worked on the X1! The plasmashell crash on 26.04 caught a few people off guard. Good specs by the way.
Interesting, they point to google chrome as culprit.
I'm a firefox user but had been messing with chrome today and had the same problem.
Really glad it worked. The Chrome/Chromium connection is becoming clearer from these comments, Brave, Chrome, same Chromium base, same problem. It looks like v154 is writing something on first launch that triggers the fontconfig race condition. The fix works regardless of the trigger, but knowing the root cause helps. On the subreddit suggestion: good idea :)
I can confirm that Brave caused this problem for me on a new install of Kubuntu 26.04 and that the permanent fix above did the trick. I first had the problem with 24.04 which brought me here. I decided to go ahead with a fresh install of 26.04 instead of fixing 24.04. Everything was fine until I installed Brave. I rebooted before installing Brave and again after which is when plasma crashed.
Thanks for the tips, they are a life saver.
That is a clean reproduction actually. Fresh install, everything fine, Brave installed, reboot, crash. That pretty much confirms Brave as the trigger. Good that the fix held on 26.04 as well.
I forgot to add that I did install some extensions into Brave before rebooting ... Dark Reader and Group Speed Dial. Not impossible that they had an effect. I'm going to install 26.04 on my laptop too so I'll reboot before adding the extension on that.
Interesting detail. Extensions run their own install routines so it is possible one of them touched something in the font or config directory. Worth testing on the laptop with a clean reboot before and after extensions. If the crash happens without extensions installed, that narrows it down to Brave itself.
Thanks a lot for this excellent fix.
I had the same issue after an update of several apps on Kubuntu 26.04. I am not a specialist, but I am wondering about Google Chrome or KCalc as the origin of the problem. True, I also use Google Chrome 154 ( 154.0.8037.57) and there was a recent update. However, in my case, the plasmashell crash occurred after a KCalc crash (KDE's simple calculator). A crash message mentioned that KCalc had stopped working. I cleared (root) /var/crash and restarted the computer, and then the plasmashell crash happened for the first time. Again, this may have nothing to do with it and I am no specialist, but I have read on other forums that after a KCalc crash you precisely have to clear fontconfig by:
rm -rf ~/.cache/fontconfig/
Would the KCalc crash be a consequence of the Chrome fontconfig issue, or would it be the origin of the plasmashell crash?
Exactly right. Qt uses fontconfig under the hood for text rendering, which is why the crash spreads across KDE applications. Chromium writes something on first launch that corrupts the cache, and then anything built on Qt that tries to read it fails. The systemd drop-in fixes it by regenerating the cache before plasmashell loads.
My guess is that Chrome triggered the fontconfig corruption first, and the KCalc crash came after as a consequence. KCalc is a Qt application and Qt uses fontconfig for rendering, so once the cache is corrupted any Qt app can crash. partd's link explains it well. The clearing of fontconfig after the KCalc crash is what temporarily fixed things for you, which confirms the cache was the common cause.
Thanks again.
The Kubuntu Focus Team considers this indeed as a Google Chrome bug:
"Although this issue is the responsibility of Google, the Kubuntu Focus Team have taken steps to monitor upcoming versions of Google Chrome to help identify and prevent distribution of a broken version like this in the future."
reddit.com/r/Kubuntu/comments/1wo8...
Good to know the Kubuntu Focus Team is on it. Makes sense that they treat it as a Chrome bug rather than a KDE or fontconfig bug. The cache corruption is triggered by Chrome, the fix should come from Chrome. Until then the drop-in keeps things stable.
Thanks a lot for this post! I ran into the exact same issue after the latest update and was going crazy digging through logs. The systemd drop-in fix is incredibly clean and works perfectly. Clear, concise, and straight to the point. Thanks for sharing! 🚀
Glad it helped. The logs are the right place to start but fontconfig issues are not always obvious from them. Happy it is sorted.
After reading the comments, it is hard to believe this is just a Chromium/Chrome bug. Any application running under user permission could intentionally corrupt fontcache and crash Plamas. This could potentially expose to Local Code Execution. Someone from Plasma should have Vul bug opened and fix the issue, so Plasma can handle corrupted font cache file gracefully.
That is a fair point. The real fix should be in Plasma handling a corrupted or partially written font cache gracefully instead of segfaulting. The systemd drop-in is a workaround that prevents the race condition, not a solution to the underlying fragility. Worth opening a bug on the KDE tracker if it has not been done already.
Thank you so much for this solution! Worked like a charm.
This happened after an update and restart today, and looking at my update history I see brave-browser on the list, and none of the other candidates seem like things that would have caused this kind of issue.
Brave makes total sense. It shares the same Chromium base as Chrome, so the same behavior on first launch. You are probably the third person today confirming that connection. Glad it worked.
Thank you! This blog post brought my panel back on Kubuntu 24.04 x11! The panel just started disappearing a day ago. My system had been fine for a long time. I update regularly, but I don't know what caused the problem. Also, strange was that rollback to a chronshield snapshot from 2 weeks ago did not fix my problem, but your blog post did. Before I found this post, I used a chatbot to troubleshoot, and while it didn't mention this post, it seemed have a lot that was in the post--just not the solution to keep the problem from coming back. I wish I saw your post earlier. Thanks again!
Really glad it helped. The fact that a two week old snapshot did not fix it suggests the trigger was something that changed in the font cache or a shared config file that the snapshot did not capture, which makes sense with what others are reporting about Chromium v154. The persistent fix with the systemd drop-in is exactly the part that most troubleshooting guides miss. Thanks for the kind words.
For peoples awareness, this appears to be an issue with a Chromium update which corrupts the users fontconfig. Affects Chromium 154.0.8037.57-1 and also Google Chrome 154 it seems.
While the fix here will work for login, you're likely to continue to get issues with Chrome/Chromium causing crashes and are better off downgrading to 153 until Chrome/Chromium is fixed or temporarily switching to an alternative browser such as Firefox.
issues.chromium.org/issues/565052667
Thanks for the Chromium issue link, that confirms it properly. Downgrading to 153 is a good call if you rely heavily on Chrome or Brave. Firefox is the cleaner option in the meantime and avoids the problem entirely. The systemd drop-in keeps plasma stable but as you say it does not fix the underlying Chromium bug.
Thank you so very much!!
You are welcome!
I very much appreciate you sharing this. It was driving me nuts.
Glad it helped. It was driving me nuts too when I first ran into it.
Saved my day. Starting to love kde. Was going back to linux mint. Saved my day!
Stay on KDE, it is worth it once you get past the initial quirks. Plasma has come a long way.
Worked like a charm and saved me a reinstall. Many thanks.
Happy it saved the reinstall. That is exactly why I documented it, went through the same thing myself.