Bug 484801

I've been able to reproduce the issue--it seems to occur after trying to unlock the screen following the display turning off (and back on) after a period of inactivity. It does not occur when unlocking prior to the display turning off.

I get the following output from kscreenlocker_greet:

Locked at 1712720826
qt.qpa.wayland: Creating a fake screen in order for Qt not to crash
file:///usr/share/plasma/look-and-feel/org.kde.breeze.desktop/contents/lockscreen/NoPasswordUnlock.qml:26: ReferenceError: tryToSwitchUser is not defined
Unlocked

This happens for me in Plasma 6.1.5. I unlock with fingerprint rather than password and then get an unnecessary unlock button that I have to click.

I was not able to reproduce the issue with password unlocking. But I have this issue when unlocking with fprintd.
Here's my log from journal:
```
Dec 26 14:47:07 work kscreenlocker_greet[46084]: pam_warn(kde-smartcard:auth): function=[pam_sm_authenticate] flags=0 service=[kde-smartcard] terminal=[<unknown>] user=[nix] ruser=[<unknown>] rhost=[<unknown>]
Dec 26 14:47:10 work kscreenlocker_greet[46084]: pam_kwallet5(kde:auth): pam_kwallet5: pam_sm_authenticate
Dec 26 14:47:10 work kscreenlocker_greet[46084]: pam_kwallet5(kde:auth): pam_kwallet5: we were already executed
Dec 26 14:47:10 work kscreenlocker_greet[46084]: pam_kwallet5(kde:setcred): pam_kwallet5: pam_sm_setcred
Dec 26 14:47:10 work kscreenlocker_greet[46084]: QEventLoop: Cannot be used without QApplication
Dec 26 14:47:10 work kscreenlocker_greet[46084]: pam_unix(kde-fingerprint:auth): unexpected response from failed conversation function
Dec 26 14:47:10 work kscreenlocker_greet[46084]: pam_unix(kde-fingerprint:auth): conversation failed
Dec 26 14:47:10 work kscreenlocker_greet[46084]: pam_unix(kde-fingerprint:auth): auth could not identify password for [nix]
Dec 26 14:47:36 work kscreenlocker_greet[48127]: qrc:/qt/qml/org/kde/breeze/components/VirtualKeyboard.qml:8:1: module "QtQuick.VirtualKeyboard" is not installed
Dec 26 14:47:36 work kscreenlocker_greet[48127]: pam_warn(kde-smartcard:auth): function=[pam_sm_authenticate] flags=0 service=[kde-smartcard] terminal=[<unknown>] user=[nix] ruser=[<unknown>] rhost=[<unknown>]
Dec 26 14:47:39 work kscreenlocker_greet[48127]: file:///nix/store/yz4jyab520qm101xmvnn271r79cv9l9r-plasma-desktop-6.2.4/share/plasma/shells/org.kde.plasma.desktop/contents/lockscreen/NoPasswordUnlock.qml:26: ReferenceError: tryToSwitchUser is not defined
Dec 26 14:47:41 work kscreenlocker_greet[48127]: pam_unix(kde-fingerprint:auth): authentication failure; logname=nix uid=1000 euid=1000 tty= ruser= rhost=  user=nix
```

DT, if you're still able to reproduce this in Plasma 6.3.4 or later, do you have fingerprint authentication set up?

(In reply to Nate Graham from comment #4)
> DT, if you're still able to reproduce this in Plasma 6.3.4 or later, do you
> have fingerprint authentication set up?

When I initially reported the bug, I did not have fingerprint authentication set up (the issue occurred on a desktop system without a fingerprint reader). I do have a system with a fingerprint reader I can test on, though. I tried to reproduce the issue on 6.3.4 by unlocking the system (both with normal password input, and with a fingerprint) following these different test conditions:

1. Locking the screen normally
2. Setting the display to turn off (and lock)
3. Putting the system to sleep

I tested these conditions in both the X and Wayland sessions. I also tested them on the original system (without fingerprint authentication) where I originally experienced the bug (although my hardware configuration isn't exactly the same, I have additional displays now). I was not able to reproduce the bug across my tests. 

Please note, however, that from what I recall, the issue was fairly sporadic. I've mostly been daily driving Kubuntu 24.04 for some time now, so regrettably, I can't comment on if this bug still occurs on occasion during regular usage.

Thanks a lot. So basically you can't reproduce it anymore on Arch running Plasma 6.3.4, but you could in the past when it was running 6.2.4? But it may still be happening anyway because you're not regularly using this machine anymore?

(In reply to Nate Graham from comment #6)
> Thanks a lot. So basically you can't reproduce it anymore on Arch running
> Plasma 6.3.4, but you could in the past when it was running 6.2.4? But it
> may still be happening anyway because you're not regularly using this
> machine anymore?

I can't comment on Plasma 6.2.4 specifically. I originally encountered and reported the bug when I was regularly using Plasma 6.0-6.0.3. Since then, that Arch install has been on a separate drive on the same machine (with Kubuntu installed on my main boot drive). I would still boot into it every so often, however. I also have a laptop (the system with the fingerprint reader I tested) that I *very* recently installed Arch with Plasma 6 to, and have not used much either.

So, I can't say with 100% certainty that the bug I experienced is gone since my usage of Plasma 6 since 6.0.3 has been infrequent, but to the best of my recollection, I have not encountered the bug in a long time.

OK, let's call it fixed for now, but do feel free to re-open this bug if you encounter the exact same issue again in the future. Thanks!