SUMMARY

Logging out of Plasma 5.27.9 on Wayland in a Fedora 39 KDE Plasma installation has occasionally led to a black screen with a text cursor flashing at the top left instead of sddm on Wayland appearing. I've seen this problem several times in the last week or so. The black screen happened 10% or less of logouts in that time. The problem might involve a race condition in which sddm-greeter sometimes doesn't start. The journal during logouts showed various errors. dbus-:1.2-org.kde.LogoutPrompt@0.service failed. Many KDE programs lost connection to the Wayland compositor. plasma-polkit-agent.service and plasma-powerdevil.service tried to restart many times and failed.

Dec 15 20:59:36 systemd[1449]: Started dbus-:1.2-org.kde.LogoutPrompt@0.service.
Dec 15 20:59:36 kwin_wayland[1546]: kf.service.services: The desktop entry file "/usr/share/applications/org.freedesktop.Xwayland.desktop" has Type= "Application" but has no Exec field.
Dec 15 20:59:36 kwin_wayland[1546]: kf.service.services: The desktop entry file "/usr/share/applications/qemu.desktop" has Type= "Application" but has no Exec field.
Dec 15 20:59:36 kernel: Lockdown: systemd-logind: hibernation is restricted; see man kernel_lockdown.7
Dec 15 20:59:36 kernel: Lockdown: systemd-logind: hibernation is restricted; see man kernel_lockdown.7
Dec 15 20:59:36 kernel: Lockdown: systemd-logind: hibernation is restricted; see man kernel_lockdown.7
Dec 15 20:59:36 ksmserver-logout-greeter[5190]: qt.qpa.wayland: Wayland does not support QWindow::requestActivate()
Dec 15 20:59:36 ksmserver-logout-greeter[5190]: qt.qpa.wayland: Wayland does not support QWindow::requestActivate()
Dec 15 20:59:39 systemd[1449]: dbus-:1.2-org.kde.LogoutPrompt@0.service: Main process exited, code=exited, status=1/FAILURE
Dec 15 20:59:39 systemd[1449]: dbus-:1.2-org.kde.LogoutPrompt@0.service: Failed with result 'exit-code'.
Dec 15 20:59:40 plasmashell[1740]: trying to show an empty dialog
Dec 15 20:59:41 plasmashell[1740]: qt.qpa.wayland: Wayland does not support QWindow::requestActivate()
Dec 15 20:59:42 systemd[1449]: Started dbus-:1.2-org.kde.LogoutPrompt@1.service.
Dec 15 20:59:43 kwin_wayland[1546]: kf.service.services: The desktop entry file "/usr/share/applications/org.freedesktop.Xwayland.desktop" has Type= "Application" but has no Exec field.
Dec 15 20:59:43 kwin_wayland[1546]: kf.service.services: The desktop entry file "/usr/share/applications/qemu.desktop" has Type= "Application" but has no Exec field.
Dec 15 20:59:43 kernel: Lockdown: systemd-logind: hibernation is restricted; see man kernel_lockdown.7
Dec 15 20:59:43 kernel: Lockdown: systemd-logind: hibernation is restricted; see man kernel_lockdown.7
Dec 15 20:59:43 kernel: Lockdown: systemd-logind: hibernation is restricted; see man kernel_lockdown.7
Dec 15 20:59:43 ksmserver-logout-greeter[5234]: qt.qpa.wayland: Wayland does not support QWindow::requestActivate()
Dec 15 20:59:43 ksmserver-logout-greeter[5234]: qt.qpa.wayland: Wayland does not support QWindow::requestActivate()
Dec 15 20:59:44 systemd[1449]: Started dbus-:1.2-org.kde.Shutdown@0.service.
Dec 15 20:59:44 systemd[1449]: dbus-:1.2-org.kde.LogoutPrompt@1.service: Main process exited, code=exited, status=1/FAILURE
Dec 15 20:59:44 systemd[1449]: dbus-:1.2-org.kde.LogoutPrompt@1.service: Failed with result 'exit-code'.
Dec 15 20:59:44 plasmashell[1740]: file:///usr/share/plasma/plasmoids/org.kde.plasma.private.systemtray/contents/ui/items/PlasmoidItem.qml:125: TypeError: Cannot read property 'compactRepresentationItem' of null
Dec 15 20:59:44 kwin_wayland_wrapper[1643]: (EE) failed to read Wayland events: Connection reset by peer
Dec 15 20:59:44 kded5[1870]: X connection to :0 broken (explicit kill or server shutdown).
Dec 15 20:59:44 kaccess[2108]: The X11 connection broke (error 1). Did the X11 server die?
Dec 15 20:59:44 systemd[1449]: app-kaccess@autostart.service: Main process exited, code=exited, status=1/FAILURE
Dec 15 20:59:44 systemd[1449]: app-kaccess@autostart.service: Failed with result 'exit-code'.
Dec 15 20:59:44 kwin_wayland[1546]: QtDBus: cannot relay signals from parent QObject(0x55839bc3c020 "") unless they are emitted in the object's thread QThread(0x55839bb8ad68 "libinput-connection"). Current thread is QThread(0x55839b93c140 "").
Dec 15 20:59:44 kwalletd5[1490]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 kwalletd5[1490]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 kded5[1693]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 plasmashell[1740]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 xdg-desktop-portal-kde[1792]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 xdg-desktop-portal-kde[1792]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 xdg-desktop-por[1851]: Lost connection to Wayland compositor.
Dec 15 20:59:44 polkit-kde-authentication-agent-1[1787]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 evolution-alarm[2064]: Lost connection to Wayland compositor.
Dec 15 20:59:44 kactivitymanagerd[1785]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 akonadi_indexing_agent[2480]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 kdeconnectd[2074]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 akonadi_maildir_resource[2482]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 org_kde_powerdevil[1789]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 seapplet[2084]: Error reading events from display: Broken pipe
Dec 15 20:59:44 DiscoverNotifier[2116]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 kalendarac[2123]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 akonadi_control[2333]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 akonadi_birthdays_resource[2469]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 akonadi_unifiedmailbox_agent[2491]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 akonadi_mailfilter_agent[2485]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 akonadi_mailfilter_agent[2485]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 systemd[1449]: app-org.gnome.Evolution\x2dalarm\x2dnotify@autostart.service: Main process exited, code=exited, status=1/FAILURE
Dec 15 20:59:44 systemd[1449]: app-org.gnome.Evolution\x2dalarm\x2dnotify@autostart.service: Failed with result 'exit-code'.
Dec 15 20:59:44 akonadi_akonotes_resource[2467]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 akonadi_mailmerge_agent[2486]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 systemd[1449]: plasma-kded.service: Main process exited, code=exited, status=1/FAILURE
Dec 15 20:59:44 systemd[1449]: plasma-kded.service: Failed with result 'exit-code'.
Dec 15 20:59:44 akonadi_mailmerge_agent[2486]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 systemd[1449]: plasma-kded.service: Consumed 1.872s CPU time.
Dec 15 20:59:44 akonadi_followupreminder_agent[2478]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 systemd[1449]: plasma-kactivitymanagerd.service: Main process exited, code=exited, status=1/FAILURE
Dec 15 20:59:44 akonadi_migration_agent[2487]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 systemd[1449]: plasma-kactivitymanagerd.service: Failed with result 'exit-code'.
Dec 15 20:59:44 akonadi_ical_resource[2479]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 akonadi_maildispatcher_agent[2483]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 akonadi_newmailnotifier_agent[2488]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 akonadi_archivemail_agent[2468]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 systemd[1449]: plasma-polkit-agent.service: Main process exited, code=exited, status=1/FAILURE
Dec 15 20:59:44 systemd[1449]: plasma-polkit-agent.service: Failed with result 'exit-code'.
Dec 15 20:59:44 polkitd[1045]: Unregistered Authentication Agent for unix-session:2 (system bus name :1.70, object path /org/kde/PolicyKit1/AuthenticationAgent, locale en_CA.UTF-8) (disconnected from bus)
Dec 15 20:59:44 akonadi_sendlater_agent[2490]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "AgentBaseChangeRecorder - 94877085886544" disconnected
Dec 15 20:59:44 systemd[1449]: plasma-xdg-desktop-portal-kde.service: Main process exited, code=exited, status=1/FAILURE
Dec 15 20:59:44 akonadi_contacts_resource[2470]: The Wayland connection broke. Did the Wayland compositor die?
Dec 15 20:59:44 systemd[1449]: plasma-xdg-desktop-portal-kde.service: Failed with result 'exit-code'.
Dec 15 20:59:44 systemd[1449]: xdg-desktop-portal-gtk.service: Main process exited, code=exited, status=1/FAILURE
Dec 15 20:59:44 systemd[1449]: xdg-desktop-portal-gtk.service: Failed with result 'exit-code'.
Dec 15 20:59:44 systemd[1449]: plasma-powerdevil.service: Main process exited, code=exited, status=1/FAILURE
Dec 15 20:59:44 systemd[1449]: plasma-powerdevil.service: Failed with result 'exit-code'.
Dec 15 20:59:44 systemd[1449]: app-sealertauto@autostart.service: Main process exited, code=exited, status=1/FAILURE
Dec 15 20:59:44 systemd[1449]: app-sealertauto@autostart.service: Failed with result 'exit-code'.
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "AgentBaseChangeRecorder - 94633069656672" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "AgentBaseChangeRecorder - 94119421482960" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "ETMCalendarMonitor - 94679318665936" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "AgentBaseChangeRecorder - 94734606156112" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "AgentBaseChangeRecorder - 94914604900224" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "AgentBaseChangeRecorder - 94619613548816" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "AgentBaseChangeRecorder - 94115917070880" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "akonadi_birthdays_resource - 94713733751008" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "SpecialCollectionsMonitor - 94619613603952" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "ArchiveMailCollectionMonitor - 94115917120496" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "AgentBaseChangeRecorder - 94307126651568" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "AgentBaseChangeRecorder - 94611861087600" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "AgentBaseChangeRecorder - 94713733703168" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "akonadi_maildispatcher_agent - 94619613679856" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "AgentBaseChangeRecorder - 93907791233712" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "Archive Mail Kernel ETM - 94115917215904" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "AgentBaseChangeRecorder - 94088352083392" disconnected
Dec 15 20:59:44 systemd[1449]: app-org.kde.kalendarac@autostart.service: Main process exited, code=exited, status=1/FAILURE
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "AgentBaseChangeRecorder - 94549979726080" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "UnifiedMailboxChangeRecorder - 140726108910160" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "AgentBaseChangeRecorder - 94081842604784" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "MailFilterItemMonitor - 94090202118688" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "AgentBaseChangeRecorder - 94090201955504" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "MailFilterCollectionMonitor - 94090202011296" disconnected
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "MailFilter Kernel ETM - 94090202114656" disconnected
Dec 15 20:59:44 systemd[1449]: app-org.kde.discover.notifier@autostart.service: Main process exited, code=exited, status=1/FAILURE
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Subscriber "SpecialCollectionsMonitor - 94090202328416" disconnected
Dec 15 20:59:44 systemd[1449]: app-org.kde.discover.notifier@autostart.service: Failed with result 'exit-code'.
Dec 15 20:59:44 systemd[1449]: app-org.kde.discover.notifier@autostart.service: Consumed 6.330s CPU time.
Dec 15 20:59:44 systemd[1449]: plasma-plasmashell.service: Main process exited, code=exited, status=1/FAILURE
Dec 15 20:59:44 systemd[1449]: plasma-plasmashell.service: Failed with result 'exit-code'.
Dec 15 20:59:44 systemd[1449]: plasma-plasmashell.service: Consumed 38.766s CPU time.
Dec 15 20:59:44 akonadiserver[2371]: org.kde.pim.akonadiserver: Control process died, exiting!
Dec 15 20:59:44 systemd[1449]: plasma-polkit-agent.service: Scheduled restart job, restart counter is at 1.
Dec 15 20:59:44 systemd[1449]: plasma-plasmashell.service: Scheduled restart job, restart counter is at 1.
Dec 15 20:59:44 systemd[1449]: plasma-powerdevil.service: Scheduled restart job, restart counter is at 1.
Dec 15 20:59:44 systemd[1449]: Starting plasma-plasmashell.service - KDE Plasma Workspace...
Dec 15 20:59:44 systemd[1449]: Starting plasma-polkit-agent.service - KDE PolicyKit Authentication Agent...
Dec 15 20:59:44 systemd[1449]: Starting plasma-powerdevil.service - Powerdevil...
Dec 15 20:59:45 systemd[1449]: app-org.kde.kdeconnect.daemon@autostart.service: Main process exited, code=exited, status=1/FAILURE
Dec 15 20:59:45 systemd[1449]: app-org.kde.kdeconnect.daemon@autostart.service: Failed with result 'exit-code'.
Dec 15 20:59:46 systemd[1]: systemd-timedated.service: Deactivated successfully.
Dec 15 20:59:46 audit[1]: SERVICE_STOP pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=systemd-timedated comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
Dec 15 20:59:46 audit: BPF prog-id=90 op=UNLOAD
Dec 15 20:59:46 audit: BPF prog-id=89 op=UNLOAD
Dec 15 20:59:46 audit: BPF prog-id=88 op=UNLOAD
Dec 15 20:59:48 systemd[1449]: app-org.kde.kalendarac@autostart.service: Failed with result 'exit-code'.
Dec 15 20:59:48 systemd[1449]: app-org.kde.kalendarac@autostart.service: Consumed 15.450s CPU time.
Dec 15 20:59:49 systemd[1449]: Starting plasma-xdg-desktop-portal-kde.service - Xdg Desktop Portal For KDE...
Dec 15 20:59:50 systemd[1449]: plasma-polkit-agent.service: start operation timed out. Terminating.
Dec 15 20:59:50 systemd[1449]: plasma-powerdevil.service: start operation timed out. Terminating.
Dec 15 20:59:50 systemd[1449]: plasma-polkit-agent.service: Failed with result 'timeout'.
Dec 15 20:59:50 systemd[1449]: Failed to start plasma-polkit-agent.service - KDE PolicyKit Authentication Agent.
Dec 15 20:59:50 systemd[1449]: plasma-powerdevil.service: Failed with result 'timeout'.
Dec 15 20:59:50 systemd[1449]: Failed to start plasma-powerdevil.service - Powerdevil.
Dec 15 20:59:50 systemd[1449]: plasma-polkit-agent.service: Scheduled restart job, restart counter is at 2.
Dec 15 20:59:50 systemd[1449]: plasma-powerdevil.service: Scheduled restart job, restart counter is at 2.
Dec 15 20:59:50 systemd[1449]: Starting plasma-polkit-agent.service - KDE PolicyKit Authentication Agent...
Dec 15 20:59:50 systemd[1449]: Starting plasma-powerdevil.service - Powerdevil...
Dec 15 20:59:51 systemd[1]: pcscd.service: Deactivated successfully.
Dec 15 20:59:51 audit[1]: SERVICE_STOP pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=pcscd comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
Dec 15 20:59:55 systemd[1449]: plasma-polkit-agent.service: start operation timed out. Terminating.
Dec 15 20:59:55 systemd[1449]: plasma-powerdevil.service: start operation timed out. Terminating.
Dec 15 20:59:55 systemd[1449]: plasma-polkit-agent.service: Failed with result 'timeout'.
Dec 15 20:59:55 systemd[1449]: Failed to start plasma-polkit-agent.service - KDE PolicyKit Authentication Agent.
Dec 15 20:59:55 systemd[1449]: plasma-powerdevil.service: Failed with result 'timeout'.
Dec 15 20:59:55 systemd[1449]: Failed to start plasma-powerdevil.service - Powerdevil.
Dec 15 20:59:55 systemd[1449]: plasma-polkit-agent.service: Scheduled restart job, restart counter is at 3.
Dec 15 20:59:55 systemd[1449]: plasma-powerdevil.service: Scheduled restart job, restart counter is at 3.
Dec 15 20:59:55 systemd[1449]: Starting plasma-polkit-agent.service - KDE PolicyKit Authentication Agent...
Dec 15 20:59:55 systemd[1449]: Starting plasma-powerdevil.service - Powerdevil...
Dec 15 21:00:01 systemd[1449]: plasma-polkit-agent.service: start operation timed out. Terminating.
Dec 15 21:00:01 systemd[1449]: plasma-powerdevil.service: start operation timed out. Terminating.
Dec 15 21:00:01 systemd[1449]: plasma-polkit-agent.service: Failed with result 'timeout'.
Dec 15 21:00:01 systemd[1449]: Failed to start plasma-polkit-agent.service - KDE PolicyKit Authentication Agent.
Dec 15 21:00:01 systemd[1449]: plasma-powerdevil.service: Failed with result 'timeout'.
Dec 15 21:00:01 systemd[1449]: Failed to start plasma-powerdevil.service - Powerdevil.
Dec 15 21:00:01 systemd[1449]: plasma-polkit-agent.service: Scheduled restart job, restart counter is at 4.
Dec 15 21:00:01 systemd[1449]: plasma-powerdevil.service: Scheduled restart job, restart counter is at 4.
Dec 15 21:00:01 systemd[1449]: Starting plasma-polkit-agent.service - KDE PolicyKit Authentication Agent...
Dec 15 21:00:01 systemd[1449]: Starting plasma-powerdevil.service - Powerdevil...
Dec 15 21:00:06 systemd[1449]: plasma-polkit-agent.service: start operation timed out. Terminating.
Dec 15 21:00:06 systemd[1449]: plasma-powerdevil.service: start operation timed out. Terminating.
Dec 15 21:00:06 systemd[1449]: plasma-polkit-agent.service: Failed with result 'timeout'.
Dec 15 21:00:06 systemd[1449]: Failed to start plasma-polkit-agent.service - KDE PolicyKit Authentication Agent.
Dec 15 21:00:06 systemd[1449]: plasma-powerdevil.service: Failed with result 'timeout'.
Dec 15 21:00:06 systemd[1449]: Failed to start plasma-powerdevil.service - Powerdevil.
Dec 15 21:00:06 systemd[1449]: plasma-polkit-agent.service: Scheduled restart job, restart counter is at 5.
Dec 15 21:00:06 systemd[1449]: plasma-powerdevil.service: Scheduled restart job, restart counter is at 5.
Dec 15 21:00:06 systemd[1449]: Starting plasma-polkit-agent.service - KDE PolicyKit Authentication Agent...
Dec 15 21:00:06 systemd[1449]: Starting plasma-powerdevil.service - Powerdevil...
Dec 15 21:00:12 systemd[1449]: plasma-polkit-agent.service: start operation timed out. Terminating.
Dec 15 21:00:12 systemd[1449]: plasma-powerdevil.service: start operation timed out. Terminating.
Dec 15 21:00:12 systemd[1449]: plasma-polkit-agent.service: Failed with result 'timeout'.
Dec 15 21:00:12 systemd[1449]: Failed to start plasma-polkit-agent.service - KDE PolicyKit Authentication Agent.
Dec 15 21:00:12 systemd[1449]: plasma-powerdevil.service: Failed with result 'timeout'.
Dec 15 21:00:12 systemd[1449]: Failed to start plasma-powerdevil.service - Powerdevil.
Dec 15 21:00:12 systemd[1449]: plasma-polkit-agent.service: Scheduled restart job, restart counter is at 6.
Dec 15 21:00:12 systemd[1449]: plasma-powerdevil.service: Scheduled restart job, restart counter is at 6.
Dec 15 21:00:12 systemd[1449]: Starting plasma-polkit-agent.service - KDE PolicyKit Authentication Agent...
Dec 15 21:00:12 systemd[1449]: Starting plasma-powerdevil.service - Powerdevil...
Dec 15 21:00:17 systemd[1449]: plasma-polkit-agent.service: start operation timed out. Terminating.
Dec 15 21:00:17 systemd[1449]: plasma-powerdevil.service: start operation timed out. Terminating.
Dec 15 21:00:17 systemd[1449]: plasma-polkit-agent.service: Failed with result 'timeout'.
Dec 15 21:00:17 systemd[1449]: Failed to start plasma-polkit-agent.service - KDE PolicyKit Authentication Agent.
Dec 15 21:00:17 systemd[1449]: plasma-powerdevil.service: Failed with result 'timeout'.
Dec 15 21:00:17 systemd[1449]: Failed to start plasma-powerdevil.service - Powerdevil.
Dec 15 21:00:17 systemd[1449]: plasma-polkit-agent.service: Scheduled restart job, restart counter is at 7.
Dec 15 21:00:17 systemd[1449]: plasma-powerdevil.service: Scheduled restart job, restart counter is at 7.
Dec 15 21:00:17 systemd[1449]: Starting plasma-polkit-agent.service - KDE PolicyKit Authentication Agent...
Dec 15 21:00:17 systemd[1449]: Starting plasma-powerdevil.service - Powerdevil...
Dec 15 21:00:23 systemd[1449]: plasma-polkit-agent.service: start operation timed out. Terminating.
Dec 15 21:00:23 systemd[1449]: plasma-powerdevil.service: start operation timed out. Terminating.
Dec 15 21:00:23 systemd[1449]: plasma-polkit-agent.service: Failed with result 'timeout'.
Dec 15 21:00:23 systemd[1449]: Failed to start plasma-polkit-agent.service - KDE PolicyKit Authentication Agent.
Dec 15 21:00:23 systemd[1449]: plasma-powerdevil.service: Failed with result 'timeout'.
Dec 15 21:00:23 systemd[1449]: Failed to start plasma-powerdevil.service - Powerdevil.
Dec 15 21:00:23 systemd[1449]: plasma-polkit-agent.service: Scheduled restart job, restart counter is at 8.
Dec 15 21:00:23 systemd[1449]: plasma-powerdevil.service: Scheduled restart job, restart counter is at 8.
Dec 15 21:00:23 systemd[1449]: Starting plasma-polkit-agent.service - KDE PolicyKit Authentication Agent...
Dec 15 21:00:23 systemd[1449]: Starting plasma-powerdevil.service - Powerdevil...
Dec 15 21:00:28 systemd[1449]: plasma-polkit-agent.service: start operation timed out. Terminating.
Dec 15 21:00:28 systemd[1449]: plasma-powerdevil.service: start operation timed out. Terminating.
Dec 15 21:00:28 systemd[1449]: plasma-polkit-agent.service: Failed with result 'timeout'.
Dec 15 21:00:28 systemd[1449]: Failed to start plasma-polkit-agent.service - KDE PolicyKit Authentication Agent.
Dec 15 21:00:28 systemd[1449]: plasma-powerdevil.service: Failed with result 'timeout'.
Dec 15 21:00:28 systemd[1449]: Failed to start plasma-powerdevil.service - Powerdevil.
Dec 15 21:00:28 systemd[1449]: plasma-polkit-agent.service: Scheduled restart job, restart counter is at 9.
Dec 15 21:00:28 systemd[1449]: plasma-powerdevil.service: Scheduled restart job, restart counter is at 9.
Dec 15 21:00:28 systemd[1449]: Starting plasma-polkit-agent.service - KDE PolicyKit Authentication Agent...
Dec 15 21:00:28 systemd[1449]: Starting plasma-powerdevil.service - Powerdevil...
Dec 15 21:00:34 systemd[1449]: plasma-polkit-agent.service: start operation timed out. Terminating.
Dec 15 21:00:34 systemd[1449]: plasma-powerdevil.service: start operation timed out. Terminating.
Dec 15 21:00:34 systemd[1449]: plasma-polkit-agent.service: Failed with result 'timeout'.
Dec 15 21:00:34 systemd[1449]: Failed to start plasma-polkit-agent.service - KDE PolicyKit Authentication Agent.
Dec 15 21:00:34 systemd[1449]: plasma-powerdevil.service: Failed with result 'timeout'.
Dec 15 21:00:34 systemd[1449]: Failed to start plasma-powerdevil.service - Powerdevil.
Dec 15 21:00:34 systemd[1449]: plasma-polkit-agent.service: Scheduled restart job, restart counter is at 10.
Dec 15 21:00:34 systemd[1449]: plasma-powerdevil.service: Scheduled restart job, restart counter is at 10.
Dec 15 21:00:34 systemd[1449]: Starting plasma-polkit-agent.service - KDE PolicyKit Authentication Agent...
Dec 15 21:00:34 systemd[1449]: Starting plasma-powerdevil.service - Powerdevil...
Dec 15 21:00:34 systemd[1449]: plasma-xdg-desktop-portal-kde.service: start operation timed out. Terminating.
Dec 15 21:00:34 systemd[1449]: plasma-xdg-desktop-portal-kde.service: Failed with result 'timeout'.
Dec 15 21:00:34 systemd[1449]: Failed to start plasma-xdg-desktop-portal-kde.service - Xdg Desktop Portal For KDE.
Dec 15 21:00:34 xdg-desktop-por[1573]: Failed to get application states: GDBus.Error:org.freedesktop.DBus.Error.NameHasNoOwner: Could not activate remote peer: startup job failed.
Dec 15 21:00:39 systemd[1449]: plasma-powerdevil.service: start operation timed out. Terminating.
Dec 15 21:00:39 systemd[1449]: plasma-polkit-agent.service: start operation timed out. Terminating.
Dec 15 21:00:39 systemd[1449]: Starting plasma-xdg-desktop-portal-kde.service - Xdg Desktop Portal For KDE...
Dec 15 21:00:39 systemd[1449]: plasma-polkit-agent.service: Failed with result 'timeout'.
Dec 15 21:00:39 systemd[1449]: Failed to start plasma-polkit-agent.service - KDE PolicyKit Authentication Agent.
Dec 15 21:00:39 systemd[1449]: plasma-powerdevil.service: Failed with result 'timeout'.
Dec 15 21:00:39 systemd[1449]: Failed to start plasma-powerdevil.service - Powerdevil.
Dec 15 21:00:39 systemd[1449]: plasma-polkit-agent.service: Scheduled restart job, restart counter is at 11.
Dec 15 21:00:39 systemd[1449]: plasma-powerdevil.service: Scheduled restart job, restart counter is at 11.
Dec 15 21:00:39 systemd[1449]: Starting plasma-polkit-agent.service - KDE PolicyKit Authentication Agent...
Dec 15 21:00:39 systemd[1449]: Starting plasma-powerdevil.service - Powerdevil...
Dec 15 21:00:44 systemd[1449]: plasma-polkit-agent.service: start operation timed out. Terminating.
Dec 15 21:00:44 systemd[1449]: plasma-powerdevil.service: start operation timed out. Terminating.
Dec 15 21:00:44 systemd[1449]: plasma-polkit-agent.service: Failed with result 'timeout'.
Dec 15 21:00:44 systemd[1449]: Failed to start plasma-polkit-agent.service - KDE PolicyKit Authentication Agent.
Dec 15 21:00:44 systemd[1449]: plasma-powerdevil.service: Failed with result 'timeout'.
Dec 15 21:00:44 systemd[1449]: Failed to start plasma-powerdevil.service - Powerdevil.
Dec 15 21:00:45 systemd[1449]: plasma-polkit-agent.service: Scheduled restart job, restart counter is at 12.
Dec 15 21:00:45 systemd[1449]: plasma-powerdevil.service: Scheduled restart job, restart counter is at 12.
Dec 15 21:00:45 systemd[1449]: Starting plasma-polkit-agent.service - KDE PolicyKit Authentication Agent...
Dec 15 21:00:45 systemd[1449]: Starting plasma-powerdevil.service - Powerdevil...
Dec 15 21:00:50 systemd[1449]: plasma-polkit-agent.service: start operation timed out. Terminating.
Dec 15 21:00:50 systemd[1449]: plasma-powerdevil.service: start operation timed out. Terminating.
Dec 15 21:00:50 systemd[1449]: plasma-polkit-agent.service: Failed with result 'timeout'.
Dec 15 21:00:50 systemd[1449]: Failed to start plasma-polkit-agent.service - KDE PolicyKit Authentication Agent.
Dec 15 21:00:50 systemd[1449]: plasma-powerdevil.service: Failed with result 'timeout'.
Dec 15 21:00:50 systemd[1449]: Failed to start plasma-powerdevil.service - Powerdevil.
Dec 15 21:00:50 systemd[1449]: plasma-polkit-agent.service: Scheduled restart job, restart counter is at 13.
Dec 15 21:00:50 systemd[1449]: plasma-powerdevil.service: Scheduled restart job, restart counter is at 13.
Dec 15 21:00:50 systemd[1449]: Starting plasma-polkit-agent.service - KDE PolicyKit Authentication Agent...
Dec 15 21:00:50 systemd[1449]: Starting plasma-powerdevil.service - Powerdevil...
Dec 15 21:00:55 systemd[1449]: plasma-polkit-agent.service: start operation timed out. Terminating.
Dec 15 21:00:55 systemd[1449]: plasma-powerdevil.service: start operation timed out. Terminating.
Dec 15 21:00:55 systemd[1449]: plasma-polkit-agent.service: Failed with result 'timeout'.
Dec 15 21:00:55 systemd[1449]: Failed to start plasma-polkit-agent.service - KDE PolicyKit Authentication Agent.
Dec 15 21:00:55 systemd[1449]: plasma-powerdevil.service: Failed with result 'timeout'.
Dec 15 21:00:55 systemd[1449]: Failed to start plasma-powerdevil.service - Powerdevil.
Dec 15 21:00:56 systemd[1449]: plasma-polkit-agent.service: Scheduled restart job, restart counter is at 14.
Dec 15 21:00:56 systemd[1449]: plasma-powerdevil.service: Scheduled restart job, restart counter is at 14.
Dec 15 21:00:56 systemd[1449]: Starting plasma-polkit-agent.service - KDE PolicyKit Authentication Agent...
Dec 15 21:00:56 systemd[1449]: Starting plasma-powerdevil.service - Powerdevil...
Dec 15 21:00:58 systemd[1]: Started getty@tty3.service - Getty on tty3.
Dec 15 21:00:58 audit[1]: SERVICE_START pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=getty@tty3 comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
Dec 15 21:00:58 uresourced[1235]: Setting resources on user-1000.slice (MemoryMin: 0, MemoryLow: 0, CPUWeight: 100, IOWeight: 100)
Dec 15 21:00:58 uresourced[1235]: Setting resources on user@1000.service (MemoryMin: 0, MemoryLow: 0, CPUWeight: 100, IOWeight: 100)
Dec 15 21:00:58 uresourced[1235]: Setting resources on user.slice (MemoryMin: 0, MemoryLow: 0, CPUWeight: -, IOWeight: -)
Dec 15 21:01:01 systemd[1449]: plasma-polkit-agent.service: start operation timed out. Terminating.
Dec 15 21:01:01 systemd[1449]: plasma-powerdevil.service: start operation timed out. Terminating.
Dec 15 21:01:01 systemd[1449]: plasma-polkit-agent.service: Failed with result 'timeout'.
Dec 15 21:01:01 systemd[1449]: Failed to start plasma-polkit-agent.service - KDE PolicyKit Authentication Agent.
Dec 15 21:01:01 systemd[1449]: plasma-powerdevil.service: Failed with result 'timeout'.
Dec 15 21:01:01 systemd[1449]: Failed to start plasma-powerdevil.service - Powerdevil.
Dec 15 21:01:01 systemd[1449]: plasma-polkit-agent.service: Scheduled restart job, restart counter is at 15.
Dec 15 21:01:01 systemd[1449]: plasma-powerdevil.service: Scheduled restart job, restart counter is at 15.
Dec 15 21:01:01 systemd[1449]: Starting plasma-polkit-agent.service - KDE PolicyKit Authentication Agent...
Dec 15 21:01:01 systemd[1449]: Starting plasma-powerdevil.service - Powerdevil...
Dec 15 21:01:01 dbus-broker-launch[989]: Activation request for 'net.reactivated.Fprint' failed: The systemd unit 'fprintd.service' is masked.
Dec 15 21:01:01 login[5513]: pam_fprintd(login:auth): GetDevices failed: Could not activate remote peer: activation request failed: unit is masked.
Dec 15 21:01:01 CROND[5531]: (root) CMD (run-parts /etc/cron.hourly)
Dec 15 21:01:01 run-parts[5534]: (/etc/cron.hourly) starting 0anacron
Dec 15 21:01:02 run-parts[5540]: (/etc/cron.hourly) finished 0anacron
Dec 15 21:01:02 CROND[5530]: (root) CMDEND (run-parts /etc/cron.hourly)
Dec 15 21:01:06 audit[5513]: USER_AUTH pid=5513 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:local_login_t:s0-s0:c0.c1023 msg='op=PAM:authentication grantors=pam_usertype,pam_localuser,pam_unix acct="matt" exe="/usr/bin/login" hostname=localhost.localdomain addr=? terminal=/dev/tty3 res=success'
Dec 15 21:01:06 audit[5513]: USER_ACCT pid=5513 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:local_login_t:s0-s0:c0.c1023 msg='op=PAM:accounting grantors=pam_unix,pam_localuser acct="matt" exe="/usr/bin/login" hostname=localhost.localdomain addr=? terminal=/dev/tty3 res=success'
Dec 15 21:01:06 audit[5513]: CRED_ACQ pid=5513 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:local_login_t:s0-s0:c0.c1023 msg='op=PAM:setcred grantors=pam_localuser,pam_unix acct="matt" exe="/usr/bin/login" hostname=localhost.localdomain addr=? terminal=/dev/tty3 res=success'
Dec 15 21:01:06 audit[5513]: USER_ROLE_CHANGE pid=5513 uid=0 auid=1000 ses=4 subj=system_u:system_r:local_login_t:s0-s0:c0.c1023 msg='pam: default-context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 selected-context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 exe="/usr/bin/login" hostname=localhost.localdomain addr=? terminal=/dev/tty3 res=success'

I switched to another VT when the problem happened. I ran sudo systemctl restart sddm. sddm appeared. plasmashell and powerdevil crashed repeatedly after that.

STEPS TO REPRODUCE
1. Boot a Fedora 39 KDE Plasma installation updated to 2023-12-21 with updates-testing enabled
2. Log in to Plasma on Wayland from sddm
3. Log out of Plasma
4. If the black screen problem didn't happen, repeat 2-3 until it does

OBSERVED RESULT
Logging out of Plasma occasionally led to a black screen instead of sddm appearing

EXPECTED RESULT
Logging out of Plasma should have always resulted in sddm appearing

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora 39
(available in About System)
KDE Plasma Version: 5.27.9
KDE Frameworks Version: 5.111.0
Qt Version: 5.15.11

ADDITIONAL INFORMATION

This problem was similar to https://bugzilla.redhat.com/show_bug.cgi?id=2179591 but was much less frequent. That problem only happened with the second or third user on the system, while this one happens with both the first and second user.
That problem was in sddm. https://bugs.kde.org/show_bug.cgi?id=467547 https://github.com/sddm/sddm/pull/1701
I reported this problem at https://bugzilla.redhat.com/show_bug.cgi?id=2254935