Bug 430695

Summary:	Empty black screen with mouse pointer which is movable after computer wakeup
Product:	[Unmaintained] kscreenlocker	Reporter:	yP6pxFJmSpO2xZwPW <fuxfwgc4a2i1gr>
Component:	greeter	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	RESOLVED FIXED
Severity:	normal	CC:	677ee1vp, aleixpol, bshah, nate, reinhold
Priority:	NOR
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Ubuntu
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:	5.25.0
Sentry Crash Report:

Description yP6pxFJmSpO2xZwPW 2020-12-22 07:06:45 UTC

SUMMARY
Empty black screen with mouse pointer which is movable after computer wakeup from sleep instead of sddm login screen.
Issue possible temporary to fix without reboot only using actions . Issue appeared first time in kubuntu 20.04. 
1) Switch to console (ctrl+alt+f2)
2) Login
3) kill kcheckpass and kscreenlocker
4) after it possible to return to GUI and SDDM login screen now visible

For temporary workaround at kubuntu 20.04 it was enough to kill kcheckpass only
For temporary workaround at kubuntu 20.10 need to kill kcheckpass and kscreenlocker. 

STEPS TO REPRODUCE
1. Press leave -> (Sleep) Suspend to ram 
2. Wait until computer sleep
3. press any button to wake up

OBSERVED RESULT
Empty black screen with mouse pointer which is movable.

EXPECTED RESULT
SDDM login screen must be on screen

SOFTWARE/OS VERSIONS

Operating System: Kubuntu 20.10
KDE Plasma Version: 5.19.5
KDE Frameworks Version: 5.74.0
Qt Version: 5.14.2
Kernel Version: 5.8.0-33-generic
OS Type: 64-bit
Processors: 8 × Intel® Core™ i7-6700K CPU @ 4.00GHz
Memory: 31,3 GiB of RAM
Graphics Processor: GeForce GTX 1070/PCIe/SSE2

ADDITIONAL INFORMATION

Comment 1 Reinhold Kainhofer 2021-01-02 11:01:47 UTC

I can confirm this issue on my laptop. Before the Upgrade, on Ubuntu 20.04 (using gdm3 on kubuntu with plasma) I had a similar behaviour as the OP (no black screen after a screen lock, but rather a screenshot of all open windows! -> Cursor moved, but no window reacted and no password field was displayed, either), but was able to get the password field on the lockscreen by pressing Ctrl+Alt+F1. 

However, after the upgrade to Ubuntu 20.20 and switching to sddm, I need to switch to a text terminal and kill kcheckpass (killing kscreenlocker is not needed on my machine). After that, the login field on the lock screen is properly displayed and I can unlock the session.

CPU: 8x Intel(R) Core(TM) i5-8250U CPU @ 1.60GHz
Graphics Processor: 
00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 620 (rev 07)
01:00.0 3D controller: NVIDIA Corporation GM108M [GeForce 930MX] (rev a2)

Comment 2 Nate Graham 2021-06-21 22:47:49 UTC

Failing to show the greeter, maybe?

Comment 3 Aleix Pol 2022-09-20 00:10:31 UTC

We can probably assume this to be fixed. kcheckpass is not a thing anymore.