can this be reproduced with full debug packages installed?
(at least plasma-workspace and kconfig)

can you post here those two files?
plasmashellrc
and
plasma-org.kde.plasma.desktop-appletsrc

Hi,

attaching requested files and trace with debugs.

I also noticed that this happen only with auto login. If I logout and login then there is no crash.

Created attachment 104431 [details]
crash

Created attachment 104432 [details]
plasma-org.kde.plasma.desktop-appletsrc

Created attachment 104433 [details]
plasmashellrc

pasting inline backtrace

Thread 1 (Thread 0x7f7b278cf3c0 (LWP 1565)):
[KCrash Handler]
#6  0x00007f7b3632689b in QExplicitlySharedDataPointer<KConfigGroupPrivate>::operator!() const (this=<optimized out>) at /usr/include/qt5/QtCore/qshareddata.h:210
#7  0x00007f7b3632689b in KConfigGroupPrivate::fullName() const (this=0x0) at /usr/src/debug/kconfig-5.31.0/src/core/kconfiggroup.cpp:86
#8  0x00007f7b36325c29 in KConfigGroup::readEntry(char const*, QVariant const&) const (this=this@entry=0x7ffe30eb5670, key=key@entry=0x55da0aefc458 "alignment", aDefault=...) at /usr/src/debug/kconfig-5.31.0/src/core/kconfiggroup.cpp:719
#9  0x000055da0aeb4bda in KConfigGroup::readEntry<int>(char const*, int const&) const (this=this@entry=0x7ffe30eb5670, key=key@entry=0x55da0aefc458 "alignment", defaultValue=@0x7ffe30eb5650: 1) at /usr/include/KF5/KConfigCore/kconfiggroup.h:723
#10 0x000055da0aeb28f5 in PanelView::restore() (this=this@entry=0x55da0c28a8e0) at /usr/src/debug/plasma-workspace-5.8.6/shell/panelview.cpp:494
#11 0x000055da0aeb2bc4 in PanelView::containmentChanged() (this=0x55da0c28a8e0) at /usr/src/debug/plasma-workspace-5.8.6/shell/panelview.cpp:1049
#12 0x000055da0aeb436d in PanelView::qt_static_metacall(QObject*, QMetaObject::Call, int, void**) (_o=0x55da0c28a8e0, _c=<optimized out>, _id=<optimized out>, _a=<optimized out>) at /usr/src/debug/plasma-workspace-5.8.6/x86_64-redhat-linux-gnu/shell/moc_panelview.cpp:234
#13 0x00007f7b35546721 in QMetaObject::activate(QObject*, int, int, void**) (sender=0x55da0c28a8e0, signalOffset=<optimized out>, local_signal_index=local_signal_index@entry=2, argv=argv@entry=0x0) at kernel/qobject.cpp:3740
#14 0x00007f7b35546fc7 in QMetaObject::activate(QObject*, QMetaObject const*, int, void**) (sender=<optimized out>, m=m@entry=0x7f7b3b39f720 <PlasmaQuick::ContainmentView::staticMetaObject>, local_signal_index=local_signal_index@entry=2, argv=argv@entry=0x0) at kernel/qobject.cpp:3602
#15 0x00007f7b3b17b0b3 in PlasmaQuick::ContainmentView::containmentChanged() (this=<optimized out>) at /usr/src/debug/plasma-framework-5.31.0/x86_64-redhat-linux-gnu/src/plasmaquick/moc_containmentview.cpp:261
#16 0x00007f7b3b17b4c9 in PlasmaQuick::ContainmentViewPrivate::setContainment(Plasma::Containment*) (this=0x55da0bfe61f0, cont=0x55da0b3c6fa0) at /usr/src/debug/plasma-framework-5.31.0/src/plasmaquick/containmentview.cpp:96
#17 0x00007f7b3b17bf09 in PlasmaQuick::ContainmentView::setContainment(Plasma::Containment*) (this=this@entry=0x55da0c28a8e0, cont=<optimized out>) at /usr/src/debug/plasma-framework-5.31.0/src/plasmaquick/containmentview.cpp:258
#18 0x000055da0aebe7d8 in ShellCorona::createWaitingPanels() (this=0x55da0b334ca0) at /usr/src/debug/plasma-workspace-5.8.6/shell/shellcorona.cpp:1275
#19 0x00007f7b35546a56 in QtPrivate::QSlotObjectBase::call(QObject*, void**) (a=0x7ffe30eb5be0, r=0x55da0b334ca0, this=<optimized out>) at ../../src/corelib/kernel/qobject_impl.h:101
#20 0x00007f7b35546a56 in QMetaObject::activate(QObject*, int, int, void**) (sender=sender@entry=0x55da0b334d60, signalOffset=<optimized out>, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x0) at kernel/qobject.cpp:3723
#21 0x00007f7b35546fc7 in QMetaObject::activate(QObject*, QMetaObject const*, int, void**) (sender=sender@entry=0x55da0b334d60, m=m@entry=0x7f7b3575bda0 <QTimer::staticMetaObject>, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x0) at kernel/qobject.cpp:3602
#22 0x00007f7b355b6890 in QTimer::timeout(QTimer::QPrivateSignal) (this=this@entry=0x55da0b334d60) at .moc/moc_qtimer.cpp:198
#23 0x00007f7b35552c08 in QTimer::timerEvent(QTimerEvent*) (this=0x55da0b334d60, e=<optimized out>) at kernel/qtimer.cpp:254
#24 0x00007f7b3554779b in QObject::event(QEvent*) (this=0x55da0b334d60, e=<optimized out>) at kernel/qobject.cpp:1285
#25 0x00007f7b35debecc in QApplicationPrivate::notify_helper(QObject*, QEvent*) (this=<optimized out>, receiver=0x55da0b334d60, e=0x7ffe30eb5f00) at kernel/qapplication.cpp:3799
#26 0x00007f7b35df3671 in QApplication::notify(QObject*, QEvent*) (this=0x7ffe30eb62c0, receiver=0x55da0b334d60, e=0x7ffe30eb5f00) at kernel/qapplication.cpp:3556
#27 0x00007f7b3551f6fa in QCoreApplication::notifyInternal2(QObject*, QEvent*) (receiver=0x55da0b334d60, event=event@entry=0x7ffe30eb5f00) at kernel/qcoreapplication.cpp:988
#28 0x00007f7b3556cceb in QCoreApplication::sendEvent(QObject*, QEvent*) (event=0x7ffe30eb5f00, receiver=<optimized out>) at ../../src/corelib/kernel/qcoreapplication.h:231
#29 0x00007f7b3556cceb in QTimerInfoList::activateTimers() (this=0x55da0b2d5b50) at kernel/qtimerinfo_unix.cpp:644
#30 0x00007f7b3556d241 in timerSourceDispatch(GSource*, GSourceFunc, gpointer) (source=<optimized out>) at kernel/qeventdispatcher_glib.cpp:182
#31 0x00007f7b2d2d5e52 in g_main_dispatch (context=0x7f7b180016f0) at gmain.c:3203
#32 0x00007f7b2d2d5e52 in g_main_context_dispatch (context=context@entry=0x7f7b180016f0) at gmain.c:3856
#33 0x00007f7b2d2d61d0 in g_main_context_iterate (context=context@entry=0x7f7b180016f0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at gmain.c:3929
#34 0x00007f7b2d2d627c in g_main_context_iteration (context=0x7f7b180016f0, may_block=may_block@entry=1) at gmain.c:3990
#35 0x00007f7b3556d6cf in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x55da0b2f2030, flags=...) at kernel/qeventdispatcher_glib.cpp:423
#36 0x00007f7b3551e68a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (this=this@entry=0x7ffe30eb6150, flags=..., flags@entry=...) at kernel/qeventloop.cpp:212
#37 0x00007f7b3552618c in QCoreApplication::exec() () at kernel/qcoreapplication.cpp:1261
#38 0x000055da0ae9f752 in main(int, char**) (argc=<optimized out>, argv=<optimized out>) at /usr/src/debug/plasma-workspace-5.8.6/shell/main.cpp:166

Git commit d602198f6807bbfa175b6aaaa1bdf1708fce703e by Marco Martin.
Committed on 22/05/2017 at 15:39.
Pushed by mart into branch 'Plasma/5.10'.

don't check for panel visible during startup

if any kscreen related activities occurred
during startup, the panel wouldn't be visible
yet, and this would assert. This often happens
when a screen gets disabled at startup

M  +1    -0    shell/panelview.cpp
M  +5    -1    shell/shellcorona.cpp

https://commits.kde.org/plasma-workspace/d602198f6807bbfa175b6aaaa1bdf1708fce703e

Git commit 6602e991617cf857c262ac3fbb2ac00c7de1fb15 by Marco Martin.
Committed on 22/05/2017 at 15:43.
Pushed by mart into branch 'master'.

don't check for panel visible during startup

if any kscreen related activities occurred
during startup, the panel wouldn't be visible
yet, and this would assert. This often happens
when a screen gets disabled at startup

M  +1    -0    shell/panelview.cpp
M  +5    -1    shell/shellcorona.cpp

https://commits.kde.org/plasma-workspace/6602e991617cf857c262ac3fbb2ac00c7de1fb15

this commit may have helped, but with a different crash, still can't reproduce locally that exact backtrace

I have a similar Issue with 
Qt: 5.12.4
KF5: 5.62.0
Kubuntu: 19.10
Xorg
It does not crash but i get a black screen w/ only a kicker on it. I have to run kwin_x11 --replace then my desktop comes up by its shifted to the far right of my screen i can only see 1/4 of it. Changing the settings in the display config does not help. I have to use the laptops hot keys to switch to unified display then back to external only.

Thank you for the report.

As this was reported on an older version of plasmashell, can you please test on a recent and confirm if this issue is still occurring or if this bug report can be marked as resolved.

I have set the bug status to "needsinfo" pending your response, please change back to "reported" or "resolved/worksforme" when you respond, thank you.

This is no longer happening for me 

PlasmaShell: 5.18.5
KDE Frameworks: 5.58.0
Qt: 5.12.8
Kubuntu: 20.04

I'll leave as waiting info so the OP can confirm.

I can confirm that this is no longer the case