It is an x86_64 Cooker system kept up to date with “dnf --allowerasing distro-syc”.
System boots to sddm login just fine. When logging in to plasma desktop the system displays desktop momentarily and then goes to black screen with mouse cursor. The issue started approx. a week ago. As I recall the issue started before the aborted mass rebuild in Cooker x86_64 happened. (Not 100% positive of that though.)
If I am fast enough I will see these errors displayed graphically before VBox/plasmashell craps out:
VBox errors: VBoxClient: Failed to get display change request, rc=VERR_ACCESS_DENIED…
VBox errors: VBoxClient: Failed to register resizing support, rc=VERR_INVALID_FUNCTION…
journalctl -b log: Cooker/VBox-broken-plasmashell - Pastebin.com
xorg-session.log: xorg-session.log-broken-plasmashell - Pastebin.com
Let me know if any other logs or info is needed or tests to be done.