Bug 448211 - Sessions are breaking all the time when starting from standby on Debian with Wayland - it shows a black screen with "the screen locker is broken"
Summary: Sessions are breaking all the time when starting from standby on Debian with ...
Status: REPORTED
Alias: None
Product: kscreenlocker
Classification: Plasma
Component: general (show other bugs)
Version: unspecified
Platform: Debian stable Linux
: NOR crash
Target Milestone: ---
Assignee: Plasma Bugs List
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2022-01-10 14:34 UTC by myndstream
Modified: 2024-04-11 16:06 UTC (History)
7 users (show)

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Description myndstream 2022-01-10 14:34:58 UTC
SUMMARY
Since I switched to Wayland on Debian11/KDE starting the computer from standby often shows a black screen with the notice that one should use ctrl+alt+f2 and loginctl unlock-session {id} (this text disappears before one can fully read it). Doing so doesn't help (and running ctrl+alt+f7 shows a frozen login-screen) but running pkill -KILL -u {username} does.

After running that command and pressing ctrl+alt+F(8 for example) in the login screen a qemu user is shown again, even though I reran this https://unix.stackexchange.com/a/663937/233262 as a workaround to at least hide the user.

After pressing ctrl+alt+F(8 for example) to show to login screen after logging the user out it shortly shows the error "Failed to start LSB: web-based administration interface for Unix systems" before loading the login screen (and I don't have webmin installed anymore). Moreover, since recently, the VeraCrypt-mounted drive isn't showing as mounted in VeraCrypt anymore in the GUI (but it's still mounted). No veracrypt process is running. Another thing that's happening with these crashes is that the bashhistory file is only around 20kB large, everything else got removed (which means every time I restore the history from the backups).

Related bug about troubleshooting and logs for Wayland problems: https://bugs.kde.org/show_bug.cgi?id=447769

If this bug should be filed for kwin instead, please move it there.

(I do know that Debian11 doesn't use the latest version of KDE.)

Slightly more details and logs here: https://unix.stackexchange.com/q/684498/233262 

STEPS TO REPRODUCE
1. Switch to Wayland on Debian11/KDE
2. Use the system for a while (sometimes it takes days until this occurs again, right after switching this occurred far more often than now)

OBSERVED RESULT
Session breaks with a black screen showing an error message for a time that's too short to even read it

EXPECTED RESULT
Sessions shouldn't break.
And if they do there should be better error handling. If a black screen is shown it should keep showing the error message and if possible also show ways to solve the problem. Lastly, there should be guides on how to troubleshoot problems like this and logs that help solve such issues.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Debian 11
KDE Plasma Version: 5.20.5
KDE Frameworks Version: 5.78.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION
Comment 1 myndstream 2022-04-13 11:19:37 UTC
Currently in about 90% of starts from standby one needs to press ctrl+alt+F(8 for example)  then run loginctl unlock-session {id} to reopen the running session without having to enter a password.

This is a critical bug and a security problem. Why is this the case in Debian11?

It (this) still occurs.
Comment 2 Arne v.Irmer 2022-10-21 13:18:27 UTC
The bug is still there.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Manjaro/Archlinux 
KDE Plasma Version: 5.25.5
KDE Frameworks Version: 5.98.0
Qt Version: 5.15.6
Comment 3 myndstream 2022-10-28 16:47:52 UTC
Didn't remember this bug report and it may be caused by kscreenlocker: https://bugs.kde.org/show_bug.cgi?id=461123
Please leave a comment if there's another bug to track or already a solution or workaround
Comment 4 Frank Dekervel 2023-10-26 09:22:30 UTC
for me this is the way to reproduce it:

* suspend laptop
* disconnect external screen while the laptop is suspended
* resume laptop from suspend

i'm on 5.27.9.1 (ubuntu)
Comment 5 Maarten Steevens 2024-03-22 12:57:42 UTC
I was hoping it might be fixed in plasma 6.0 because wayland is now the default. But the bug still occurs to this day with plasma 6.0.2 on kde neon. The steps posted to reproduce the bug where you unplug a monitor while your laptop sleeps are still valid. I run into this issue multiple times every day (basically every time I wake up my laptop). In my case it happens because my external monitor (connect over usb-c) wakes up slightly too slow so it's practically the same thing as if it was unplugged when waking it from sleep. One trick I sometimes use is to manually wake up my monitor by pressing one of its buttons and then waking up my laptop.
Comment 6 myndstream 2024-04-11 16:06:56 UTC
After upgrading to Debian12 and switching to Wayland this is not happening anymore. There are or were other issues with the screen locker but not this one anymore.