Application: systemsettings5 (5.14.3)
 (Compiled from sources)
Qt Version: 5.11.2
Frameworks Version: 5.52.0
Operating System: Linux 4.15.0-39-generic x86_64
Distribution: KDE neon User Edition 5.14

-- Information about the crash:
- Unusual behavior I noticed:
after the crash with the attached report, a monitor connected via usb-c to dvi adapter was detected to only support VGA resolution (640x480). after restarting the process the orgin resolution was available again.

The crash can be reproduced sometimes.

-- Backtrace:
Application: Systemeinstellungen (systemsettings5), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7feea9381840 (LWP 2733))]

Thread 6 (Thread 0x7fee63fff700 (LWP 2780)):
#0  0x00007feea497c0b4 in __GI___libc_read (fd=20, buf=0x7fee63ffeb9e, nbytes=10) at ../sysdeps/unix/sysv/linux/read.c:27
#1  0x00007fee7e6beff1 in pa_read () from /usr/lib/x86_64-linux-gnu/pulseaudio/libpulsecommon-11.1.so
#2  0x00007fee7eb429fe in pa_mainloop_prepare () from /usr/lib/x86_64-linux-gnu/libpulse.so.0
#3  0x00007fee7eb43470 in pa_mainloop_iterate () from /usr/lib/x86_64-linux-gnu/libpulse.so.0
#4  0x00007fee7eb43530 in pa_mainloop_run () from /usr/lib/x86_64-linux-gnu/libpulse.so.0
#5  0x00007fee7eb51399 in ?? () from /usr/lib/x86_64-linux-gnu/libpulse.so.0
#6  0x00007fee7e6ee2a8 in ?? () from /usr/lib/x86_64-linux-gnu/pulseaudio/libpulsecommon-11.1.so
#7  0x00007feea00946db in start_thread (arg=0x7fee63fff700) at pthread_create.c:463
#8  0x00007feea498d88f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 5 (Thread 0x7fee6ebab700 (LWP 2741)):
#0  0x00007feea4980bf9 in __GI___poll (fds=0x7fee68004e00, nfds=1, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007fee9dcd6539 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fee9dcd664c in g_main_context_iteration () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007feea52bb04b in QEventDispatcherGlib::processEvents (this=0x7fee68000b20, flags=...) at kernel/qeventdispatcher_glib.cpp:424
#4  0x00007feea525f30a in QEventLoop::exec (this=this@entry=0x7fee6ebaad40, flags=..., flags@entry=...) at kernel/qeventloop.cpp:214
#5  0x00007feea508abba in QThread::exec (this=<optimized out>) at thread/qthread.cpp:525
#6  0x00007feea30bc4f5 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#7  0x00007feea5095adb in QThreadPrivate::start (arg=0x55e07a8ce530) at thread/qthread_unix.cpp:367
#8  0x00007feea00946db in start_thread (arg=0x7fee6ebab700) at pthread_create.c:463
#9  0x00007feea498d88f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 4 (Thread 0x7fee75b1e700 (LWP 2739)):
#0  0x00007feea497c0b4 in __GI___libc_read (fd=14, buf=0x7fee75b1db30, nbytes=16) at ../sysdeps/unix/sysv/linux/read.c:27
#1  0x00007fee9dd1acd0 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fee9dcd6027 in g_main_context_check () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fee9dcd64e0 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007fee9dcd664c in g_main_context_iteration () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007feea52bb04b in QEventDispatcherGlib::processEvents (this=0x7fee70000b20, flags=...) at kernel/qeventdispatcher_glib.cpp:424
#6  0x00007feea525f30a in QEventLoop::exec (this=this@entry=0x7fee75b1dd40, flags=..., flags@entry=...) at kernel/qeventloop.cpp:214
#7  0x00007feea508abba in QThread::exec (this=<optimized out>) at thread/qthread.cpp:525
#8  0x00007feea30bc4f5 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#9  0x00007feea5095adb in QThreadPrivate::start (arg=0x55e0746115e0) at thread/qthread_unix.cpp:367
#10 0x00007feea00946db in start_thread (arg=0x7fee75b1e700) at pthread_create.c:463
#11 0x00007feea498d88f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 3 (Thread 0x7fee7d8d7700 (LWP 2738)):
#0  0x00007feea497c0b4 in __GI___libc_read (fd=13, buf=0x7fee7d8d6b30, nbytes=16) at ../sysdeps/unix/sysv/linux/read.c:27
#1  0x00007fee9dd1acd0 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fee9dcd6027 in g_main_context_check () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fee9dcd64e0 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007fee9dcd664c in g_main_context_iteration () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007feea52bb04b in QEventDispatcherGlib::processEvents (this=0x7fee78000b20, flags=...) at kernel/qeventdispatcher_glib.cpp:424
#6  0x00007feea525f30a in QEventLoop::exec (this=this@entry=0x7fee7d8d6d40, flags=..., flags@entry=...) at kernel/qeventloop.cpp:214
#7  0x00007feea508abba in QThread::exec (this=<optimized out>) at thread/qthread.cpp:525
#8  0x00007feea30bc4f5 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#9  0x00007feea5095adb in QThreadPrivate::start (arg=0x55e0742bee80) at thread/qthread_unix.cpp:367
#10 0x00007feea00946db in start_thread (arg=0x7fee7d8d7700) at pthread_create.c:463
#11 0x00007feea498d88f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 2 (Thread 0x7fee8d586700 (LWP 2736)):
#0  0x00007feea4980bf9 in __GI___poll (fds=0x7fee88004db0, nfds=1, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007fee9dcd6539 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fee9dcd664c in g_main_context_iteration () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007feea52bb04b in QEventDispatcherGlib::processEvents (this=0x7fee88000b20, flags=...) at kernel/qeventdispatcher_glib.cpp:424
#4  0x00007feea525f30a in QEventLoop::exec (this=this@entry=0x7fee8d585d30, flags=..., flags@entry=...) at kernel/qeventloop.cpp:214
#5  0x00007feea508abba in QThread::exec (this=<optimized out>) at thread/qthread.cpp:525
#6  0x00007feea5701e45 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5DBus.so.5
#7  0x00007feea5095adb in QThreadPrivate::start (arg=0x7feea5979d60) at thread/qthread_unix.cpp:367
#8  0x00007feea00946db in start_thread (arg=0x7fee8d586700) at pthread_create.c:463
#9  0x00007feea498d88f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 1 (Thread 0x7feea9381840 (LWP 2733)):
[KCrash Handler]
#6  QString::QString (other=<error reading variable: Cannot access memory at address 0x10>, this=this@entry=0x7ffeeee5eed0) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qstring.h:952
#7  KScreen::Mode::id (this=this@entry=0x0) at ./src/mode.cpp:69
#8  0x00007fee6ee10da7 in OutputConfig::slotResolutionChanged (this=0x55e07a9f8ee0, size=...) at ./kcm/src/outputconfig.cpp:185
#9  0x00007feea529018f in QtPrivate::QSlotObjectBase::call (a=0x7ffeeee5f030, r=0x55e07a9f8ee0, this=0x55e07a959930) at ../../include/QtCore/../../src/corelib/kernel/qobjectdefs_impl.h:376
#10 QMetaObject::activate (sender=sender@entry=0x55e07a9f4470, signalOffset=<optimized out>, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x7ffeeee5f030) at kernel/qobject.cpp:3754
#11 0x00007feea5290747 in QMetaObject::activate (sender=sender@entry=0x55e07a9f4470, m=m@entry=0x7fee6f0329e0 <ResolutionSlider::staticMetaObject>, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x7ffeeee5f030) at kernel/qobject.cpp:3633
#12 0x00007fee6ee25942 in ResolutionSlider::resolutionChanged (this=this@entry=0x55e07a9f4470, _t1=...) at ./obj-x86_64-linux-gnu/kcm/src/kcm_kscreen_autogen/EWIEGA46WW/moc_resolutionslider.cpp:140
#13 0x00007fee6ee1700b in ResolutionSlider::slotValueChanged (this=0x55e07a9f4470, value=<optimized out>) at ./kcm/src/resolutionslider.cpp:164
#14 0x00007feea529018f in QtPrivate::QSlotObjectBase::call (a=0x7ffeeee5f1b0, r=0x55e07a9f4470, this=0x55e07a9978a0) at ../../include/QtCore/../../src/corelib/kernel/qobjectdefs_impl.h:376
#15 QMetaObject::activate (sender=sender@entry=0x55e07a9f4b60, signalOffset=<optimized out>, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x7ffeeee5f1b0) at kernel/qobject.cpp:3754
#16 0x00007feea5290747 in QMetaObject::activate (sender=sender@entry=0x55e07a9f4b60, m=m@entry=0x7feea694cec0 <QAbstractSlider::staticMetaObject>, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x7ffeeee5f1b0) at kernel/qobject.cpp:3633
#17 0x00007feea636500e in QAbstractSlider::valueChanged (this=this@entry=0x55e07a9f4b60, _t1=<optimized out>, _t1@entry=1) at .moc/moc_qabstractslider.cpp:304
#18 0x00007feea63656cb in QAbstractSlider::setValue (this=this@entry=0x55e07a9f4b60, value=1) at widgets/qabstractslider.cpp:546
#19 0x00007feea6365912 in QAbstractSlider::triggerAction (this=this@entry=0x55e07a9f4b60, action=action@entry=QAbstractSlider::SliderMove) at widgets/qabstractslider.cpp:635
#20 0x00007feea6366315 in QAbstractSliderPrivate::scrollByDelta (this=0x55e079165640, orientation=<optimized out>, modifiers=..., delta=<optimized out>) at widgets/qabstractslider.cpp:750
#21 0x00007feea63664a5 in QAbstractSlider::wheelEvent (this=<optimized out>, e=0x7ffeeee5f450) at widgets/qabstractslider.cpp:770
#22 0x00007feea62bba98 in QWidget::event (this=this@entry=0x55e07a9f4b60, event=event@entry=0x7ffeeee5f450) at kernel/qwidget.cpp:9287
#23 0x00007feea6366585 in QAbstractSlider::event (this=this@entry=0x55e07a9f4b60, e=e@entry=0x7ffeeee5f450) at widgets/qabstractslider.cpp:956
#24 0x00007feea640e61a in QSlider::event (this=0x55e07a9f4b60, event=0x7ffeeee5f450) at widgets/qslider.cpp:349
#25 0x00007feea627ce1c in QApplicationPrivate::notify_helper (this=this@entry=0x55e073e92450, receiver=receiver@entry=0x55e07a9f4b60, e=e@entry=0x7ffeeee5f450) at kernel/qapplication.cpp:3727
#26 0x00007feea6285e97 in QApplication::notify (this=<optimized out>, receiver=0x55e07a9f4b60, e=0x7ffeeee5f5d0) at kernel/qapplication.cpp:3295
#27 0x00007feea5260fe8 in QCoreApplication::notifyInternal2 (receiver=0x55e07a9f4b60, event=0x7ffeeee5f5d0) at kernel/qcoreapplication.cpp:1048
#28 0x00007feea5261034 in QCoreApplication::forwardEvent (receiver=receiver@entry=0x55e07a9f4b60, event=event@entry=0x7ffeeee5f5d0, originatingEvent=originatingEvent@entry=0x7ffeeee5f920) at kernel/qcoreapplication.cpp:1063
#29 0x00007feea62d7d64 in QWidgetWindow::handleWheelEvent (this=this@entry=0x55e073ff9420, event=event@entry=0x7ffeeee5f920) at kernel/qwidgetwindow.cpp:843
#30 0x00007feea62d927e in QWidgetWindow::event (this=0x55e073ff9420, event=0x7ffeeee5f920) at kernel/qwidgetwindow.cpp:307
#31 0x00007feea627ce1c in QApplicationPrivate::notify_helper (this=this@entry=0x55e073e92450, receiver=receiver@entry=0x55e073ff9420, e=e@entry=0x7ffeeee5f920) at kernel/qapplication.cpp:3727
#32 0x00007feea62843ef in QApplication::notify (this=0x7ffeeee5fbe0, receiver=0x55e073ff9420, e=0x7ffeeee5f920) at kernel/qapplication.cpp:3486
#33 0x00007feea5260fe8 in QCoreApplication::notifyInternal2 (receiver=receiver@entry=0x55e073ff9420, event=event@entry=0x7ffeeee5f920) at kernel/qcoreapplication.cpp:1048
#34 0x00007feea5a7cccb in QCoreApplication::sendSpontaneousEvent (event=0x7ffeeee5f920, receiver=0x55e073ff9420) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:237
#35 QGuiApplicationPrivate::processWheelEvent (e=0x7fee9000d460) at kernel/qguiapplication.cpp:2160
#36 0x00007feea5a82325 in QGuiApplicationPrivate::processWindowSystemEvent (e=e@entry=0x7fee9000d460) at kernel/qguiapplication.cpp:1820
#37 0x00007feea5a5af5b in QWindowSystemInterface::sendWindowSystemEvents (flags=...) at kernel/qwindowsysteminterface.cpp:1032
#38 0x00007fee9868976b in QPAEventDispatcherGlib::processEvents (this=0x55e073ee43e0, flags=...) at qeventdispatcher_glib.cpp:70
#39 0x00007feea525f30a in QEventLoop::exec (this=this@entry=0x7ffeeee5fb00, flags=..., flags@entry=...) at kernel/qeventloop.cpp:214
#40 0x00007feea52684d0 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1336
#41 0x000055e073ae7e69 in main (argc=<optimized out>, argv=<optimized out>) at ./app/main.cpp:71

Reported using DrKonqi