kde crashes when powering on/off monitor

[William Söderberg]

Whenever I turn off and on my monitor, kde crashes. The result is that the entire session is killed and I have to login again. I'm using mini displayport on my Intel NUC NUC5i7RYH to a Dell U2515h (displayport) monitor.

libqxcb.so seems responsible.

root@nuc:~/tmp# gdb -q /usr/bin/kactivitymanagerd CoreDump
Reading symbols from /usr/bin/kactivitymanagerd...(no debugging symbols found)...done.

warning: core file may not match specified executable file.
[New LWP 2908]
[New LWP 3140]
[New LWP 2931]
[New LWP 3552]
[New LWP 3553]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `/usr/bin/kactivitymanagerd start-daemon'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x00007fa57cabbf00 in ?? () from /usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/libqxcb.so
(gdb) display/i $pc
1: x/i $pc
=> 0x7fa57cabbf00: mov 0x18,%rax
(gdb) i r $rax
rax 0x1 1

Jul 30 22:48:23 nuc kernel: [18519.759137] kactivitymanage[1840]: segfault at 18 ip 00007f46d5b84f00 sp 00007ffdf4a771a8 error 4 in libqxcb.so[7f46d5b56000+b9000]
Jul 30 22:48:25 nuc kernel: [18521.315188] krunner[8512]: segfault at 18 ip 00007f3ff99a9059 sp 00007ffd753db050 error 4 in libqxcb.so[7f3ff995f000+b9000]
Jul 30 22:48:25 nuc kernel: [18521.432567] plasmashell[8519]: segfault at 18 ip 00007f925e077059 sp 00007ffe529060f0 error 4 in libqxcb.so[7f925e02d000+b9000]
Jul 30 22:48:25 nuc kernel: [18521.433509] kwin_x11[8515]: segfault at 18 ip 00007fdfb8b3f059 sp 00007ffcb7cffe80 error 4 in libqxcb.so[7fdfb8af5000+b9000]
Jul 30 22:48:25 nuc kernel: [18521.918341] klauncher[8532]: segfault at 18 ip 00007fd714eb0059 sp 00007fffd87d56e0 error 4 in libqxcb.so[7fd714e66000+b9000]
Jul 30 22:49:01 nuc kernel: [18557.068214] kdeconnectd[1818]: segfault at 18 ip 00007fe2892dae46 sp 00007ffc13c11f98 error 4 in libqxcb.so[7fe2892ac000+b9000]
Jul 30 22:49:01 nuc kernel: [18557.078143] kwrited[1848]: segfault at 18 ip 00007f5ae198be46 sp 00007ffff0b905e8 error 4 in libqxcb.so[7f5ae195d000+b9000]

Reproducible: Always

Steps to Reproduce:
1. Turn off monitor
2. Turn on monitor
3. Behaviour differs if you wait a while (1-2h maybe) before you turn on the monitor again. If you do it at once, the monitor goes into sleep mode. Then you have to switch tty (ctrl + alt + f1), kill all user processes, which will spawn a new session. If you wait and turn on the monitor, a new session will be started automatically.

Actual Results:
Jul 30 22:48:23 nuc kernel: [18519.759137] kactivitymanage[1840]: segfault at 18 ip 00007f46d5b84f00 sp 00007ffdf4a771a8 error 4 in libqxcb.so[7f46d5b56000+b9000]
Jul 30 22:48:25 nuc kernel: [18521.315188] krunner[8512]: segfault at 18 ip 00007f3ff99a9059 sp 00007ffd753db050 error 4 in libqxcb.so[7f3ff995f000+b9000]
Jul 30 22:48:25 nuc kernel: [18521.432567] plasmashell[8519]: segfault at 18 ip 00007f925e077059 sp 00007ffe529060f0 error 4 in libqxcb.so[7f925e02d000+b9000]
Jul 30 22:48:25 nuc kernel: [18521.433509] kwin_x11[8515]: segfault at 18 ip 00007fdfb8b3f059 sp 00007ffcb7cffe80 error 4 in libqxcb.so[7fdfb8af5000+b9000]
Jul 30 22:48:25 nuc kernel: [18521.918341] klauncher[8532]: segfault at 18 ip 00007fd714eb0059 sp 00007fffd87d56e0 error 4 in libqxcb.so[7fd714e66000+b9000]
Jul 30 22:49:01 nuc kernel: [18557.068214] kdeconnectd[1818]: segfault at 18 ip 00007fe2892dae46 sp 00007ffc13c11f98 error 4 in libqxcb.so[7fe2892ac000+b9000]
Jul 30 22:49:01 nuc kernel: [18557.078143] kwrited[1848]: segfault at 18 ip 00007f5ae198be46 sp 00007ffff0b905e8 error 4 in libqxcb.so[7f5ae195d000+b9000]

Expected Results:
Let the user continue work with in his/her's session.

Jul 30 22:48:23 nuc kernel: [18519.759137] kactivitymanage[1840]: segfault at 18 ip 00007f46d5b84f00 sp 00007ffdf4a771a8 error 4 in libqxcb.so[7f46d5b56000+b9000]
Jul 30 22:48:25 nuc kernel: [18521.315188] krunner[8512]: segfault at 18 ip 00007f3ff99a9059 sp 00007ffd753db050 error 4 in libqxcb.so[7f3ff995f000+b9000]
Jul 30 22:48:25 nuc kernel: [18521.432567] plasmashell[8519]: segfault at 18 ip 00007f925e077059 sp 00007ffe529060f0 error 4 in libqxcb.so[7f925e02d000+b9000]
Jul 30 22:48:25 nuc kernel: [18521.433509] kwin_x11[8515]: segfault at 18 ip 00007fdfb8b3f059 sp 00007ffcb7cffe80 error 4 in libqxcb.so[7fdfb8af5000+b9000]
Jul 30 22:48:25 nuc kernel: [18521.918341] klauncher[8532]: segfault at 18 ip 00007fd714eb0059 sp 00007fffd87d56e0 error 4 in libqxcb.so[7fd714e66000+b9000]
Jul 30 22:48:55 nuc systemd[1]: Started Session c1 of user kws.
Jul 30 22:48:55 nuc systemd[1]: Starting Session c1 of user kws.
Jul 30 22:49:00 nuc org.kde.kglobalaccel[1656]: Unregistering key "Volume Mute" for "kmix" : "mute"
Jul 30 22:49:00 nuc console-kit-daemon[1582]: missing action
Jul 30 22:49:00 nuc systemd[1448]: Reached target Shutdown.
Jul 30 22:49:00 nuc systemd[1448]: Starting Shutdown.
Jul 30 22:49:00 nuc systemd[1448]: Starting Exit the Session...
Jul 30 22:49:00 nuc systemd[1448]: Stopped target Default.
Jul 30 22:49:00 nuc systemd[1448]: Stopping Default.
Jul 30 22:49:00 nuc systemd[1448]: Stopped target Basic System.
Jul 30 22:49:00 nuc systemd[1448]: Stopping Basic System.
Jul 30 22:49:00 nuc systemd[1448]: Stopped target Paths.
Jul 30 22:49:00 nuc systemd[1448]: Stopping Paths.
Jul 30 22:49:00 nuc systemd[1448]: Stopped target Timers.
Jul 30 22:49:00 nuc systemd[1448]: Stopping Timers.
Jul 30 22:49:00 nuc systemd[1448]: Stopped target Sockets.
Jul 30 22:49:00 nuc systemd[1448]: Stopping Sockets.
Jul 30 22:49:00 nuc systemd[1448]: Received SIGRTMIN+24 from PID 8656 (kill).
Jul 30 22:49:01 nuc kernel: [18557.068214] kdeconnectd[1818]: segfault at 18 ip 00007fe2892dae46 sp 00007ffc13c11f98 error 4 in libqxcb.so[7fe2892ac000+b9000]
Jul 30 22:49:01 nuc kernel: [18557.078143] kwrited[1848]: segfault at 18 ip 00007f5ae198be46 sp 00007ffff0b905e8 error 4 in libqxcb.so[7f5ae195d000+b9000]
Jul 30 22:49:01 nuc bluetoothd[820]: bluetoothd[820]: Endpoint unregistered: sender=:1.45 path=/MediaEndpoint/BlueZ4/HFPAG
Jul 30 22:49:01 nuc bluetoothd[820]: Endpoint unregistered: sender=:1.45 path=/MediaEndpoint/BlueZ4/HFPAG
Jul 30 22:49:01 nuc bluetoothd[820]: bluetoothd[820]: Endpoint unregistered: sender=:1.45 path=/MediaEndpoint/BlueZ4/HFPHS
Jul 30 22:49:01 nuc bluetoothd[820]: Endpoint unregistered: sender=:1.45 path=/MediaEndpoint/BlueZ4/HFPHS
Jul 30 22:49:01 nuc bluetoothd[820]: bluetoothd[820]: Endpoint unregistered: sender=:1.45 path=/MediaEndpoint/BlueZ4/A2DPSource
Jul 30 22:49:01 nuc bluetoothd[820]: Endpoint unregistered: sender=:1.45 path=/MediaEndpoint/BlueZ4/A2DPSource
Jul 30 22:49:01 nuc bluetoothd[820]: Endpoint unregistered: sender=:1.45 path=/MediaEndpoint/BlueZ4/A2DPSink
Jul 30 22:49:01 nuc bluetoothd[820]: bluetoothd[820]: Endpoint unregistered: sender=:1.45 path=/MediaEndpoint/BlueZ4/A2DPSink
Jul 30 22:49:01 nuc bluetoothd[820]: bluetoothd[820]: hci0: Remove UUID (0x0011) failed: Busy (0x0a)
Jul 30 22:49:01 nuc bluetoothd[820]: hci0: Remove UUID (0x0011) failed: Busy (0x0a)
Jul 30 22:49:01 nuc acpid: client 1406[0:0] has disconnected
Jul 30 22:49:01 nuc acpid: client connected from 8675[0:0]
Jul 30 22:49:01 nuc acpid: 1 client rule loaded
Jul 30 22:49:01 nuc systemd[1]: Created slice user-115.slice.
Jul 30 22:49:01 nuc systemd[1]: Starting user-115.slice.
Jul 30 22:49:01 nuc systemd[1]: Starting User Manager for UID 115...
Jul 30 22:49:01 nuc systemd[1]: Started Session 7 of user sddm.
Jul 30 22:49:01 nuc systemd[1]: Starting Session 7 of user sddm.
Jul 30 22:49:01 nuc systemd[8683]: Reached target Timers.
Jul 30 22:49:01 nuc systemd[8683]: Starting Timers.
Jul 30 22:49:01 nuc systemd[8683]: Reached target Paths.
Jul 30 22:49:01 nuc systemd[8683]: Starting Paths.
Jul 30 22:49:01 nuc systemd[8683]: Reached target Sockets.
Jul 30 22:49:01 nuc systemd[8683]: Starting Sockets.
Jul 30 22:49:01 nuc systemd[8683]: Reached target Basic System.
Jul 30 22:49:01 nuc systemd[8683]: Starting Basic System.
Jul 30 22:49:01 nuc systemd[8683]: Reached target Default.
Jul 30 22:49:01 nuc systemd[8683]: Startup finished in 8ms.
Jul 30 22:49:01 nuc systemd[1]: Started User Manager for UID 115.
Jul 30 22:49:01 nuc systemd[8683]: Starting Default.
Jul 30 22:49:01 nuc org.kde.kglobalaccel[1656]: KCrash: Attempting to start /usr/bin/kglobalaccel5 from kdeinit
Jul 30 22:49:01 nuc org.kde.kglobalaccel[1656]: Warning: connect() failed: : Connection refused
Jul 30 22:49:01 nuc org.kde.kglobalaccel[1656]: KCrash: Attempting to start /usr/bin/kglobalaccel5 directly
Jul 30 22:49:01 nuc org.kde.kglobalaccel[1656]: KCrash: crashing... crashRecursionCounter = 2
Jul 30 22:49:01 nuc org.kde.kglobalaccel[1656]: KCrash: Application Name = kglobalaccel5 path = /usr/bin pid = 1785
Jul 30 22:49:01 nuc org.kde.kglobalaccel[1656]: KCrash: Arguments: /usr/bin/kglobalaccel5
Jul 30 22:49:02 nuc org.kde.kglobalaccel[1656]: Invalid MIT-MAGIC-COOKIE-1 keyQXcbConnection: Could not connect to display :0
Jul 30 22:49:02 nuc org.kde.kded5[8694]: Qt: Session management error: networkIdsList argument is NULL
Jul 30 22:49:02 nuc org.kde.kded5[8694]: klauncher not running... launching kdeinit
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kdeinit5: preparing to launch 'libkdeinit5_klauncher'
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kdeinit5: Launched KLauncher, pid = 8710, result = 0
Jul 30 22:49:02 nuc org.kde.kded5[8694]: Qt: Session management error: networkIdsList argument is NULL
Jul 30 22:49:02 nuc org.kde.kded5[8694]: Connecting to deprecated signal QDBusConnectionInterface::serviceOwnerChanged(QString,QString,QString)
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kdeinit5: opened connection to :0
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kdeinit5: Got EXT_EXEC '/usr/bin/kbuildsycoca5' from launcher.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kdeinit5: preparing to launch '/usr/bin/kbuildsycoca5'
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kinit.klauncher: "/usr/bin/kbuildsycoca5" (pid 8712) up and running.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kbuildsycoca5 running...
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kservice.sycoca: Trying to open ksycoca from "/var/lib/sddm/.cache/ksycoca5"
Jul 30 22:49:02 nuc org.kde.kded5[8694]: checking file timestamps
Jul 30 22:49:02 nuc org.kde.kded5[8694]: timestamps check ok
Jul 30 22:49:02 nuc org.kde.kded5[8694]: Emitting notifyDatabaseChanged ()
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kdeinit5: PID 8712 terminated.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kservice.sycoca: Trying to open ksycoca from "/var/lib/sddm/.cache/ksycoca5"
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "printmanager" still uses .desktop files ("kded/printmanager.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "notificationhelper" still uses .desktop files ("kded/notificationhelper.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "appmenu" still uses .desktop files ("kded/appmenu.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "recentdocumentsnotifier" still uses .desktop files ("kded/recentdocumentsnotifier.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "networkstatus" still uses .desktop files ("kded/networkstatus.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "solidautoeject" still uses .desktop files ("kded/solidautoeject.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "proxyscout" has already been found using JSON metadata, please don't install the now unneeded .desktop file ("kded/proxyscout.desktop").
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "powerdevil" still uses .desktop files ("kded/powerdevil.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "soliduiserver" still uses .desktop files ("kded/soliduiserver.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "khotkeys" still uses .desktop files ("kded/khotkeys.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "ktouchpadenabler" still uses .desktop files ("kded/ktouchpadenabler.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "kscreen" still uses .desktop files ("kded/kscreen.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "freespacenotifier" still uses .desktop files ("kded/freespacenotifier.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "ktimezoned" still uses .desktop files ("kded/ktimezoned.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "ksysguard" still uses .desktop files ("kded/ksysguard.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "desktopnotifier" still uses .desktop files ("kded/desktopnotifier.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "keyboard" still uses .desktop files ("kded/keyboard.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "kded_baloosearch_kio" still uses .desktop files ("kded/baloosearchfolderupdater.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "statusnotifierwatcher" still uses .desktop files ("kded/statusnotifierwatcher.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "networkwatcher" still uses .desktop files ("kded/networkwatcher.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "platformstatus" still uses .desktop files ("kded/platformstatus.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "remotedirnotify" still uses .desktop files ("kded/remotedirnotify.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "touchpad" still uses .desktop files ("kded/touchpad.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "networkmanagement" still uses .desktop files ("kded/networkmanagement.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kservice.sycoca: Trying to open ksycoca from "/var/lib/sddm/.cache/ksycoca5"
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kdeinit5: Got EXEC_NEW '/usr/lib/x86_64-linux-gnu/libexec/kf5/kconf_update' from launcher.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kdeinit5: preparing to launch '/usr/lib/x86_64-linux-gnu/libexec/kf5/kconf_update'
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kinit.klauncher: "/usr/lib/x86_64-linux-gnu/libexec/kf5/kconf_update" (pid 8713) up and running.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kdeinit5: PID 8713 terminated.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kdeinit5: Got EXT_EXEC '/usr/bin/kbuildsycoca5' from launcher.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kdeinit5: preparing to launch '/usr/bin/kbuildsycoca5'
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kinit.klauncher: "/usr/bin/kbuildsycoca5" (pid 8714) up and running.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kbuildsycoca5 running...
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kservice.sycoca: Trying to open ksycoca from "/var/lib/sddm/.cache/ksycoca5"
Jul 30 22:49:02 nuc org.kde.kded5[8694]: Reusing existing ksycoca
Jul 30 22:49:02 nuc org.kde.kded5[8694]: Recreating ksycoca file ("/var/lib/sddm/.cache/ksycoca5", version 300)
Jul 30 22:49:02 nuc org.kde.kded5[8694]: Still in the time dict (i.e. deleted files) ("apps")
Jul 30 22:49:02 nuc org.kde.kded5[8694]: Menu "applications-kmenuedit.menu" not found.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: Saving
Jul 30 22:49:02 nuc org.kde.kded5[8694]: Emitting notifyDatabaseChanged ("apps")
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kdeinit5: PID 8714 terminated.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kservice.sycoca: Trying to open ksycoca from "/var/lib/sddm/.cache/ksycoca5"
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "statusnotifierwatcher" still uses .desktop files ("kded/statusnotifierwatcher.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "notificationhelper" still uses .desktop files ("kded/notificationhelper.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "networkmanagement" still uses .desktop files ("kded/networkmanagement.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "ktouchpadenabler" still uses .desktop files ("kded/ktouchpadenabler.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "desktopnotifier" still uses .desktop files ("kded/desktopnotifier.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "ksysguard" still uses .desktop files ("kded/ksysguard.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "khotkeys" still uses .desktop files ("kded/khotkeys.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "proxyscout" has already been found using JSON metadata, please don't install the now unneeded .desktop file ("kded/proxyscout.desktop").
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "soliduiserver" still uses .desktop files ("kded/soliduiserver.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "recentdocumentsnotifier" still uses .desktop files ("kded/recentdocumentsnotifier.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "touchpad" still uses .desktop files ("kded/touchpad.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "kscreen" still uses .desktop files ("kded/kscreen.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "powerdevil" still uses .desktop files ("kded/powerdevil.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "appmenu" still uses .desktop files ("kded/appmenu.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "keyboard" still uses .desktop files ("kded/keyboard.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "remotedirnotify" still uses .desktop files ("kded/remotedirnotify.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "printmanager" still uses .desktop files ("kded/printmanager.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "ktimezoned" still uses .desktop files ("kded/ktimezoned.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "networkstatus" still uses .desktop files ("kded/networkstatus.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "kded_baloosearch_kio" still uses .desktop files ("kded/baloosearchfolderupdater.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "platformstatus" still uses .desktop files ("kded/platformstatus.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "networkwatcher" still uses .desktop files ("kded/networkwatcher.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "solidautoeject" still uses .desktop files ("kded/solidautoeject.desktop"). Please port it to JSON metadata.
Jul 30 22:49:02 nuc org.kde.kded5[8694]: kf5.kded: kded module "freespacenotifier" still uses .desktop files ("kded/freespacenotifier.desktop"). Please port it to JSON metadata.

root@nuc:/var/log# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 15.04
Release: 15.04
Codename: vivid

[Nikolay Mihaylov (nick-mihailov)]

I'm having the same problem on an up to date 15.10. Only I cannot log back in because there's no display manager present. I can switch to a virtual console and there it works. But when I get back to Console #7 the display goes into power saving mode. The only trace from the crash is in dmesg:

kactivitymanage[1629]: segfault at 18 ip 00007f4cf6438e90 sp 00007ffead511e28 error 4 in libqxcb.so[7f4cf640a000+b5000]
krunner[2159]: segfault at 18 ip 00007f3523ebede8 sp 00007ffeb62663c0 error 4 in libqxcb.so[7f3523e75000+b5000]
kwin_x11[2164]: segfault at 18 ip 00007f6e63b14de8 sp 00007fff87859850 error 4 in libqxcb.so[7f6e63acb000+b5000]
plasmashell[2167]: segfault at 18 ip 00007f192ad04de8 sp 00007ffc222dd470 error 4 in libqxcb.so[7f192acbb000+b5000]
klauncher[2176]: segfault at 18 ip 00007fb52e3abde8 sp 00007ffda395b150 error 4 in libqxcb.so[7fb52e362000+b5000]

Over DVI it works fine - I can switch my display off and on again without problems. I have a Z87 MB with Pentium G3258 using the integrated graphics of the CPU.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Nikolay Mihaylov (nick-mihailov)]

Since the bug was filed for 15.04, whereas I reported it for 15.10, I have to add that it was present for me on 15.04 as well. Only I cannot confirm whether switching to DVI helps.

Also, concerning the fact that I don't get log in screen - it seems to be the same for the original reporter. He manually kills user processes from a virtual console to get back a login screen.

And, if that's important, my display is Dell UltraSharp 2408WFP.

[William Söderberg (william-soderberg)]

I've activated kubuntu-backports and I'm now running a fully updated system (KDE 5.3). The problem still persists. I don't get the login screen if I turn off the monitor and then immediately on again. However, if I turn off the monitor when I go to bed and then turn on it again in the morning, my session is killed and I get the login screen. So, the crash actually happens when you turn on the monitor, not when you turn it off.

Please let me know what more information is required to troubleshoot this.

[juanmanuel (rockerito99)]

It affects me too with Intel NUC 5i5RYH. I have a WORKAROUND (read till the end of this post).

I have it plugged to a TV by HDMI.
Everytime the TV is switched off, X crashes with libqxcb.so errors in syslog, though the problem is not in libqxcb.so.

The problem is that xrandr looses all screen displays!! Nasty stuff. I found out about that by compiling a custom libqxcb and writing log messages to a file. This did not happen in 14.04.
Of course it won't affect laptops because they have always at least one display connected.

It also doesn't affect most desktop monitors, because when they are in standby, they don't signal that they are off in the HDMI cable signals. (pin 19).

It only affects computers on which all of their monitors or TVs get turned off without turning the computer off, and those monitors or TVs assert HDMI pin 19. My TV isn't even off, it is in standby and it asserts pin 19, which crashes linux.

Please look for HDMI PIN 19 (Hot plug detect) in the web for more information. It has caused problems in windows too in the past.

I have a nasty quick and dirty WORKAROUND:

Every time I reboot it or switch it on, I wait for X to start on the TV I have to:

     1) Wait for the UI to start. Login.
     2) In a console in the UI (such as konsole, yakuake, etc.), run this:

              xrandr --output VIRTUAL1 --mode 1920x1080 --same-as HDMI1
              xrandr --addmode VIRTUAL1 1920x1080
              xrandr --output HDMI1 --primary

      3) Now, if you run:
                xrandr
           you'll see that there is an additional display called VIRTUAL1

I tried and failed to make this sequence of commands automatic upon login in. Something about the timing about which they have to be run, when the full desktop has already been loaded I guess.

Please someone let me know if these xrandr commands can be made automatic. I'm getting "cranky" about having to run them every time the HTPC has to reboot or looses power and switch it on again.

Cheers!!
--Juan Manuel Cabo

[juanmanuel (rockerito99)]

I mean,
It is mind boggling because the main reason I got an Intel NUC was to pair it with a TV.. but it turns out that linux crashes when the TV goes to standby or OFF mode. OR HDMI gets unplugged.

I think the nvidia driver always makes sure that there is always at least one virtual or mock screen so that libraries don't crash. I think.

Cheers!
--Juan Manuel Cabo

[juanmanuel (rockerito99)]

I forgot to add:
in my tracing of libqxcb, I found that this library conflates screens with outputs.
When there are no more Outputs connected,
it returns 0 screens.

Traditionally an X screen could exist independently of its outputs.

The actual packages that will need to work to fix this very important issue are:

          libqxcb (Qt5)
          xserver-xorg-video-intel (or intel graphics driver)
          xrandr

Patching libqxcb is not enough. The crash happens later in the chain of events if so (I tried and tried).
It seems plasma and Qt5 cannot function without outputs. Other graphic environments "solve" this by always providing at least one mock or virtual output, when all physical monitors have been unplugged or asserted HotPlug pin 19 of HDMI.

--Juan Manuel Cabo

[Nikolay Mihaylov (nick-mihailov)]

I previously wrote that the problem doesn't appear over DVI. However, that's not entirely accurate. There's no problem when I turn off and on the display. But I get the very same crash when I physically remove the DVI cable. This makes sense in light of juanmanuel's posts above. And certainly should not be like this. But maybe it's an upstream problem and not sth specific to Kubuntu. I think I got the same behavior with Fedora 22. Sadly, it used to work fine prior to 15.04.

[William Söderberg (william-soderberg)]

Are everyone using Intel NUC? It seems like this issue should be more widespread. I first reported this issue to KDE, they told us to go to Kubuntu. But if Fedora has the same problem, it might be KDE related and not distribution specific? Kubuntu devs, please specify what you need from us to investigate this issue further.

[Rohan Garg (rohangarg)]

I have this on my Radeon card too, do you have a upstream bug number?

[squarooticus (krose)]

So, FYI, the NVidia driver also suffers from this: turn off a monitor and Plasma crashes; turn off both monitors and X crashes.

There is a workaround with the nvidia proprietary driver: specify your connected displays in xorg.conf. Mine looks like this:

Section "Screen"
    Identifier "Screen0"
    DefaultDepth 24
    Option "MetaModes" "DFP-4: 3840x2160 +0+0, DFP-6: 3840x2160 +3840+0"
    Option "ConnectedMonitor" "DFP-4, DFP-6"
EndSection

This says that DFP-4 and DFP-6 are connected, and have the specified initial resolutions and positions. Now, when I turn a monitor off, absolutely nothing happens: X thinks the monitor is still on, which means Plasma doesn't notice the change and doesn't crash. w00t.

The other problem I had was that even with this X wouldn't activate the second display (both are Dell P2715q) when it started because it had switched to power saving mode, so X came up in single-head mode on the same display as the virtual console. The following command line activates the second display:

xrandr --output DP-4 --pos 3840x0 --mode 3840x2160

Note that the output name doesn't match the ConnectedMonitor name from the NVidia driver. Yeah, there are two names for everything. Awesome, right?

Anyway, it would be nice to get a fix for this, but that depends on there being a way to distinguish between "I unplugged the monitor", "I shut the monitor off", and "the monitor went into power saving mode". If there isn't, then my vote is in favor of doing something intelligent in the usual case, which is that it's way more likely my monitor went into power saving mode than that I disconnected it.

[Michael Marley (mamarley)]

When 16.04 gets Qt 5.5, this is about to get a lot worse. Qt 5.5 apparently (I tested https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/landing-012) handles the monitor hotplugging differently and it causes kdeinit5 to crash (dumping me back to sddm) *every time* I move the mouse to wake the displays from sleep mode.

[Michael Marley (mamarley)]

Sorry, I forgot to mention, I have a setup very similar to ~krose with an Nvidia card and two Dell 4K monitors connected by DisplayPort.

[Thomas Bruno (tebruno99)]

This seems like a bit of a design flaw in KDE/Plasma. I've tested several other desktops are not suffering this issue with their product. Wouldn't the real bug be that Plasma cannot run without outputs?

Why are we accepting a segv as a legitimate response when all outputs vanish?

[Brunnwart (ditmar-7)]

Crash of sddm/kde/plasma/X also occurs when switching off the (only) UHD monitor connected via
- displayport under kubuntu 15.10,
- geforce 850 graphics card and nvidia-352.63 driver.
Sometimes virtual console (Strg+Alt+F1) is still accessible and X can be restarted via init 3; init 5, often not even the virtual console is visible and the computer needs a reboot.
Adding workaround of squarooticus in xorg.conf
Section "Screen"
    Identifier "Screen0"
    DefaultDepth 24
    Option "MetaModes" "DFP-3: 3840x2160 +0+0, DFP-4: 3840x2160 +3840+0"
    Option "ConnectedMonitor" "DFP-4, DFP-6"
EndSection
(where DFP-3 is the only existing monitor) did not help here.
This makes the distro unusable (and I switched from OpenSuSE to kubuntu to try a better distro :-( )

[Brunnwart (ditmar-7)]

forgot the following: what I can see in the console (Ctrl+Alt+F1) after a crash is:
policykit daemon disconnected from the bus. we are no longer a registered authentication agent

[Flames_in_Paradise (ellisistfroh-deactivatedaccount)]

hi!

would be nice if some of you could confirm bug #1516837 ([update request] SDDM 0.13.0 released on Nov. 4th) and bug #1519564 ([merge request] SDDM 0.12.0 released on Sept. 5th)

Just click on "Yes, this bug affects me too!". Once the Update (0.12) is packaged in Xenial we could ask to have it backported at least into Wily.

Was also reported upstream:
https://bugreports.qt.io/browse/QTBUG-42985 (Qt GUI application disappear or crash when no screens are available)

[Flames_in_Paradise (ellisistfroh-deactivatedaccount)]

@mmarley, comment #12: see also bug #1450137 (Qt5 applications crash when switching screens) since you are using Xenial 16.10

Removing tag= xenial here since this is another shoe, with newer version of Qt

[Alberto Salvia Novella (es20490446e)]

Please:

1. Report this bug to https://bugs.kde.org/.
2. Paste the new report URL here.
3. Set this bug status back to "confirmed".

Thank you.

[David Anderson (dga)]

I had this problem using Kubuntu 16.04 and KDE 5.5.5. A workaround that worked for me was to change the compositor via System Settings, Display and Monitor, Compositor, Rendering backend, set to XRender. I can now turn the TV off and on again without it freezing KDE.

This workaround came from the following page:
https://unix.stackexchange.com/questions/219073/how-to-enable-plasma-kde-automatic-restart-upon-freeze

[John Manko (jmanko)]

Same problem, but with gnome.