The screen locker crashes when I disconnect my external display on wayland and I'm greeted with instructions on how to unlock the session using loginctl. This does not happen on X11. I'm not sure if this happens only when disconnecting while the computer is asleep and then resuming the laptop with a different display configuration. I'll keep an on eye on this in the future.
same issue on fedora34 KDE spin with testing repos enabled (Plasma 5.22.2). Havent found much consistency yet but does appear to be an issue when the screen is disconnected too quickly. I'm not sure what 'too quickly' means exactly, maybe when laptop is asleep or if the lock screen loads slowly but external screen is disconnected when laptop is running...
When I unlocked the session plasmashell had crashed as well. Same for you?
in this case, yes it did crash but recovered without generating a gui bug report window to look into. tbh, its hard to be sure if it's the same or seperate bug as a consequence of the first crash. My laptop is 4k with an external 2560x1440 and plasma intermittently crashes when disconnecting/connecting even while at desktop (possibly this: https://bugs.kde.org/show_bug.cgi?id=438789).
Do all apps crash that you have open? If so then that means Kwin is crashing, and we need a backtrace for that. You can check for KWin crashes with coredumpctl list kwin_wayland and get the backtrace of the last crash with coredumpctl debug kwin_wayland and input "bt" when the gdb prompt appears.
No, they don't. For me only plasmashell has crashed. When I manually unlock the session all my apps are still open.
If you follow the same instructions as for Kwin but with kscreenlocker_greet can you get a backtrace?
coredumpctl lists no coredumps found for kscreenlocker_greet, hence no matches for debug. Perhaps it's been too long since the greeter's crashed, as I've been using X11 again because of this bug.
Well, if you manage to get a backtrace, do add it to the duplicate *** This bug has been marked as a duplicate of bug 439096 ***