SUMMARY For about a month - I have been unable to use two apps I prefer to use regularly - Ungoogled Chromium and Signal. Brave also has the same behavior. Firefox is NORMAL - no problem... I have not found the issue on any of the other many apps I use regularly. Each of these apps invokes a fast screen flicker with rectangular patterns superimposing over the regular display contents, then screen freezes. When I look at crash reporter contents, nothing shows up other than for Lucky Backup - and that works perfectly normally so those are probably very old crash reports. I am not 100% sure this is a kwin issue. This is a guess on my part - I have no system diagnostic info to tell me what is causing the issue. STEPS TO REPRODUCE 1. Launch one of the above listed apps. 2. Watch screen flicker almost immediately and wait. Sometimes it briefly stabilizes. Other times just keeps flickering. I am not able to use the app. Typing either does not show up -- or shows up several seconds later. 3. Try to move mouse. If I do it soon, I can successfully close the app. 4. The screen freezes and since I do not know - and haven't been able to find online a key combination to unfreeze the screen or restart Plasma, I do a hard machine power off and reboot. OBSERVED RESULT Fast flicker, then screen freeze with application still open. EXPECTED RESULT Normal use of the application software SOFTWARE/OS VERSIONS Operating System: KDE neon User Edition KDE Plasma Version: 6.4.5 KDE Frameworks Version: 6.18.0 Qt Version: 6.9.2 Kernel Version: 6.14.0-33-generic (64-bit) Graphics Platform: Wayland Processors: 8 × Intel® Core™ i7-2600 CPU @ 3.40GHz Memory: 32 GiB of RAM (31.3 GiB usable) Graphics Processor 1: AMD BARTS Graphics Processor 2: Mesa Intel® HD Graphics 2000 Manufacturer: Apple Inc. Product Name: iMac12,2 System Version: 1.0 ADDITIONAL INFORMATION I am not positive this is kwin I wish I were more skilled with bug investigation and reporting. I keep all software updated at least daily. Really appreciate all the work you put into KDE.
Can you maybe attach a video of it happening?
I ran into file size restriction trying to upload in bugzilla interface so attaching individual files as email attachments. I downsized to 480p to reduce file size... I suspect issue is related to old video card. This is a 2011 iMac. I also run KDE Neon on a 2012 iMac and have had a very good experience overall. Really hoping I'm not reaching end of life on the hardware with Linux although I understand at some point it is not feasible to support old hardware... I will send separately 2 emails: Ungoogled Chromium Brave Browser Separately: Signal Messenger On Monday, October 20th, 2025 at 2:03 AM, David Redondo <bugzilla_noreply@kde.org> wrote: > > > https://bugs.kde.org/show_bug.cgi?id=510747 > > David Redondo kde@david-redondo.de changed: > > > What |Removed |Added > ---------------------------------------------------------------------------- > CC| |kde@david-redondo.de > > --- Comment #1 from David Redondo kde@david-redondo.de --- > > Can you maybe attach a video of it happening? > > -- > You are receiving this mail because: > You reported the bug. > You are on the CC list for the bug.
Signal Messenger video On Monday, October 20th, 2025 at 7:20 AM, Peter H. Larkam <plarkam@proton.me> wrote: > > > I ran into file size restriction trying to upload in bugzilla interface so attaching individual files as email attachments. I downsized to 480p to reduce file size... > > I suspect issue is related to old video card. This is a 2011 iMac. I also run KDE Neon on a 2012 iMac and have had a very good experience overall. Really hoping I'm not reaching end of life on the hardware with Linux although I understand at some point it is not feasible to support old hardware... > > I will send separately 2 emails: > > Ungoogled Chromium > Brave Browser > > Separately: > Signal Messenger > > > > On Monday, October 20th, 2025 at 2:03 AM, David Redondo bugzilla_noreply@kde.org wrote: > > > https://bugs.kde.org/show_bug.cgi?id=510747 > > > > David Redondo kde@david-redondo.de changed: > > > > What |Removed |Added > > ---------------------------------------------------------------------------- > > CC| |kde@david-redondo.de > > > > --- Comment #1 from David Redondo kde@david-redondo.de --- > > > > Can you maybe attach a video of it happening? > > > > -- > > You are receiving this mail because: > > You reported the bug. > > You are on the CC list for the bug.
Hey David - I don't have an instantly available storage location to put the videos. I had a failure trying to upload within the bugzilla interface and then tried by email as attachments. Got quick (autoreply?) messages on file size. Please let me know if you received or did not yet receive any of the 3 videos. If not - a couple of options we can use easily: 1. If there is a standard email account that can receive an attachment of 16MB or smaller, I can send the videos to that email address. 2. If you don't want to do that, I'll create a spot in a learning management system I have and send you a link for that. You would have to "register" on the LMS to access the files. It's my own and I'm happy to delete your record when we get it resolved. Since the responses I've received are all auto-reply - I just need to know whether you have received any of the 3 videos, or if they are blocked by size constraint - I think 4MB is your limit? I have 3 example videos: Ungoogled Chromium - 10MB Brae Browser - 15.6 MB Signal Messenger - 11.3 MB If we use my LMS, I will upload 1080p versions (original iphone resolution). My email versions were 480p (sizes listed above). On Monday, October 20th, 2025 at 2:03 AM, David Redondo <bugzilla_noreply@kde.org> wrote: > > > https://bugs.kde.org/show_bug.cgi?id=510747 > > David Redondo kde@david-redondo.de changed: > > > What |Removed |Added > ---------------------------------------------------------------------------- > CC| |kde@david-redondo.de > > --- Comment #1 from David Redondo kde@david-redondo.de --- > > Can you maybe attach a video of it happening? > > -- > You are receiving this mail because: > You reported the bug. > You are on the CC list for the bug.
Created attachment 185919 [details] Brave Browser
Created attachment 185920 [details] Signal
Created attachment 185921 [details] Ungoogle Chromium Thank you for the videos, I reencoded them and uploaded them here.
What software did you use to compress the video that much?
handbrake, I just used default settings I believe
I discovered another "app" that is broken - a Jotform app. It initially flickered then stabilized but I cannot type in the entry fields. Any keyboard input is extremely delayed and garbled. I will do a full clean install on this machine with your latest KDE Neon disk image and reinstall all of my applications to see if that addresses the issue. If these symptoms are limited to my video card and you know what changed from 4-5 weeks ago, if there is a command line work-around, I'm fine with that. I don't favor you spending debugging development time for a problem that may only be occurring on my hardware...
(In reply to Peter from comment #10) > I discovered another "app" that is broken - a Jotform app. Any Electron apps would be affected by this, since they use the Chrome browser engine under the hood. So, if the Jotform app is Electron based it would suffer in the same way.
Thanks for the heads up on "Electron". Is there a command line workaround that doesn't require your team's time -- or is this a broader legitimate bug that can / will affect other users? I don't wish to consume your resources as a one-off project. I do not know if I will succeed in a clean install of KDE with my 2011 iMac machine since it uses the oldest and S L O W E S T USB interface to read the ISO file. My screen been sitting with a frozen cursor dash on black background for quite some time but I'm being patient in case it will actually load Neon and let me install. I have experienced the single dash before and time healed it... I run Plasma from internal SSD cards which are very fast but I don't have an easy way to get the ISO image as a faster external boot.
Is there a way to reset all config files to accomplish the same outcome as a clean install without having to actually do one?
(In reply to Peter from comment #13) > Is there a way to reset all config files to accomplish the same outcome as a > clean install without having to actually do one? You can try creating a new user, which would have default settings for everything. Alternatively you could try testing with a live ISO or in a VM
Thank you. New user results: no changes I can tell. I was hoping it would reset the mouse pointer / cursor issue but it does not. BTW mouse pointer is NORMAL at the login screen. After I log in - original administrator or new test standard user - mouse pointer turns to three roughly parallel squigley (sp?) lines. The first is VERY short - a few dots. Other two are maybe 2.5 cm in length and total cursor size with the 3 lines is roughly 1 cm high. Challenging to use the pointer since the actual location isn't visible - I can only tell when what I'm hovering over changes to show I'm in the zone... No idea whether this cursor issue is related to the Electron issues with Brave, Ungoogled Chromium, Signal and a JotForm app. The cursor issue is less than a week old - I think appeared with 6.5 update. The other problems appeared during 6.4.5 release. I do not know the date but pretty sure more than 30 days ago?? I will keep using existing system as it is and not try clean install since new user did not change anything... Thanks much for your help.
New Info: Different hardware (below) has different visual results: Menu items are visible but grayed out. No screen vibration. The apps appear not to launch or launch with all menus visible and not able to be selected. My cursor / mouse function is NORMAL (yea!) Apps still not functioning but different behavior. If there is any command I can use to bypass video constraints on original hardware, please advise. Operating System: KDE neon User Edition KDE Plasma Version: 6.5.0 KDE Frameworks Version: 6.19.0 Qt Version: 6.9.2 Kernel Version: 6.14.0-33-generic (64-bit) Graphics Platform: Wayland Processors: 8 × Intel® Core™ i7-3770 CPU @ 3.40GHz Memory: 32 GiB of RAM (31.3 GiB usable) Graphics Processor: llvmpipe Manufacturer: Apple Inc. Product Name: iMac13,2 System Version: 1.0
Sorry - I gave you wrong information on cursor performance. Original hardware has unusual cursor with 4 squigley lines in a rectangular pattern. Not sure how to give you a screen shot and capture it. But the cursor problem is always present on this hardware - before login and after login... Cursor may be a different bug on this video card. Trying to change cursor theme has no impact and new user has same results. Operating System: KDE neon User Edition KDE Plasma Version: 6.5.0 KDE Frameworks Version: 6.19.0 Qt Version: 6.9.2 Kernel Version: 6.14.0-33-generic (64-bit) Graphics Platform: Wayland Processors: 8 × Intel® Core™ i7-2600 CPU @ 3.40GHz Memory: 32 GiB of RAM (31.3 GiB usable) Graphics Processor 1: AMD BARTS Graphics Processor 2: Mesa Intel® HD Graphics 2000 Manufacturer: Apple Inc. Product Name: iMac12,2 System Version: 1.0
(In reply to Peter from comment #15) > Thank you. New user results: no changes I can tell. I was hoping it would > reset the mouse pointer / cursor issue but it does not. BTW mouse pointer > is NORMAL at the login screen. After I log in - original administrator or > new test standard user - mouse pointer turns to three roughly parallel > squigley (sp?) lines. It sounds like the corrupted mouse cursor graphic happens even without launching Chrome based apps, therefore it's a different bug that needs a separate report. Thanks.
The bug with the mouse cursor sounds like bug 511043, please follow that report for that issue.
I created a clean Ubuntu LTS flash installer, booted with that, and downloaded and tested Brave and Signal apps. Both work normally. So seems as though the problem is caused by something changed in Plasma and is NOT an arising from Ubuntu LTS under the hood. I wish I could pinpoint the date the problem first appeared. It was immediately after a software update - and before 6.5 release... Just wanted to report that I tested with clean Ubuntu and both Brave and Signal work normally. I did not test Ungoogled Chromium but it's very similar to Brave... If there are any tests / diagnostics I can do to facilitate a fix, happy to help. I really like using KDE Plasma / Neon and am hoping a fix can happen. This is affecting both 2011 and 2012 iMac hardware but with different results. 2011 (original report) has fast flickers 2012 has steady non-flickering desktop but the menu items on the application are gray and not able to be selected.