Created attachment 114756 [details] ksm see the attachment.
I recently upgraded my machine to 19.04 (Disco). When I want to shutdown the machine and hit "Shutdown" button. `ksmserver-logout-greeter` crashed. It is very frustrating. I upload a crash report, hope it helps.
Created attachment 119540 [details] Crash report of ksmserver-logout-greeter
Backtrace from comment #2 is unrelated. It is caused by mismatching NVIDIA driver kernel module and NVIDIA library. A reboot is needed to resolve the issue.
A possibly relevant merge request was started @ https://invent.kde.org/frameworks/kdeclarative/-/merge_requests/37
Git commit 090610124d4650150af49a8e30f6b77ad9803dfe by Nate Graham, on behalf of Piotr Henryk Dabrowski. Committed on 16/12/2020 at 21:35. Pushed by ngraham into branch 'master'. [KQuickAddons] QtQuickSettings::checkBackend() for fallback to software backend Fixes very annoying crashes of QtQuick KDE applications: ksmserver-logout-greeter, krunner (if not running before), and others occuring when the OpenGL driver stops being available (e.g. on upgrade). This issue often occurs after upgrading graphic drivers, preventing reboot, which in turn is needed for the drivers to work and not cause this crash. No changes are required in the above applications, as they all already use KQuickAddons::QtQuickSettings::init(). Related: bug 422995, bug 421493, bug 375913, bug 366156, bug 346519 M +36 -3 src/quickaddons/qtquicksettings.cpp M +2 -1 src/quickaddons/qtquicksettings.h https://invent.kde.org/frameworks/kdeclarative/commit/090610124d4650150af49a8e30f6b77ad9803dfe