Screen locker breaks every time PC is left idle for too long

I am on Fedora 42 KDE Edition, and I’ve been getting this problem almost regularly since past couple of days. Below is the exact error message.

Blockquote
The screen locker is broken and unlocking is not possible anymore. In order to unlock it, switch to a virtual terminal (e.g. Ctrl+Alt+F2), log in to your account and execute the command:
loginctl unlock-session 2
Then log out of the virtual session by pressing Ctrl+D, and switch back to the running session (Ctrl+Alt+F1).
Should you have forgotten the instructions, you can get back to this screen by pressing CTRL+ALT+F2

My laptop is supposed to “Do nothing” and only screen is supposed to turn off when kept idle, but if I leave it idle for too long (approx 30 minutes to an hour). I do not get my SDDM and have to force shutdown my PC. I suspect the latest plasma update to 6.4.1 might have caused it as this error never occurred when I was using plasma 6.3.

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Known and reported bug:

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The problem is Fedora’s update to the qt6-qtwayland package, which coincidentally was released a short time after Plasma 6.4.1.

You can see instructions on how to revert that package in the bug ticket that @moschlegbz linked to.

UPDATE: a fixed version of qt6-qtwayland,6.9.1-3, has now been released into stable Fedora 42. So a normal sudo dnf upgrade --refresh should fix.

Will give it a try, thank!

Go to Settings and change the wallpaper of the lockscreen, than click Apply. This work-around seems to do the trick.