Every once in a while plasma just crashes on startup (right after login) with the backtrace below, I have one network printer added in the list which almost certainly is never online when the crash occurs.

Thread 1 (Thread 0x7fe7f3e53800 (LWP 2472)):
[KCrash Handler]
#6  0x00007fe7edee7e37 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
#7  0x00007fe7edee9528 in __GI_abort () at abort.c:89
#8  0x00007fe7ee6291cd in qt_message_fatal (context=..., message=...) at global/qlogging.cpp:1414
#9  0x00007fe7ee6259d2 in QMessageLogger::fatal (this=0x7ffd2eacfc20, msg=0x7fe7ee98ad88 "ASSERT: \"%s\" in file %s, line %d") at global/qlogging.cpp:639
#10 0x00007fe7ee61fa9f in qt_assert (assertion=0x7fe7ee992d38 "!d->ref.isShared()", file=0x7fe7ee992d28 "tools/qlist.cpp", line=158) at global/qglobal.cpp:2810
#11 0x00007fe7ee6d56f8 in QListData::append (this=0x4e78488, n=1) at tools/qlist.cpp:158
#12 0x00007fe7ee6d581f in QListData::append (this=0x4e78488) at tools/qlist.cpp:178
#13 0x00007fe6af0cc5fe in QList<QString>::append (this=0x4e78488, t=...) at /opt/qt5/include/QtCore/qlist.h:539
#14 0x00007fe6af0cc203 in QStringList::operator<< (this=0x4e78488, str=...) at /opt/qt5/include/QtCore/qstringlist.h:87
#15 0x00007fe6af0c9db3 in KCupsConnection::connectNotify (this=0x4e78450, signal=...) at /home/mck182/kf5-dev/src/print-manager/libkcups/KCupsConnection.cpp:436
#16 0x00007fe7ee8f50c5 in QMetaObjectPrivate::connect (sender=0x4e78450, signal_index=8, smeta=0x7fe6af30f680 <KCupsConnection::staticMetaObject>, receiver=0x4e7ee40, method_index=0, rmeta=0x7fe6af30f600 <JobModel::staticMetaObject>, type=0, types=0x0) at kernel/qobject.cpp:3273
#17 0x00007fe7ee8f3499 in QObject::connect (sender=0x4e78450, signal=0x7fe6af0fb061 "serverAudit(QString)", receiver=0x4e7ee40, method=0x4e80778 "getJobs()", type=Qt::AutoConnection) at kernel/qobject.cpp:2727
#18 0x00007fe6af0e7fae in QObject::connect (this=0x4e7ee40, asender=0x4e78450, asignal=0x7fe6af0fb060 "2serverAudit(QString)", amember=0x7fe6af0fb010 "1getJobs()", atype=Qt::AutoConnection) at /opt/qt5/include/QtCore/qobject.h:479
#19 0x00007fe6af0ea5fc in JobModel::JobModel (this=0x4e7ee40, parent=0x0) at /home/mck182/kf5-dev/src/print-manager/libkcups/JobModel.cpp:129
#20 0x00007fe6af31b325 in QQmlPrivate::QQmlElement<JobModel>::QQmlElement (this=0x4e7ee40) at /opt/qt5/include/QtQml/qqmlprivate.h:93
#21 0x00007fe6af31b35f in QQmlPrivate::createInto<JobModel> (memory=0x4e7ee40) at /opt/qt5/include/QtQml/qqmlprivate.h:102
#22 0x00007fe7f0845ccb in QQmlType::create (this=0x7fe6b40373b0) at qml/qqmlmetatype.cpp:713
#23 0x00007fe7f08c8151 in QQmlObjectCreator::createInstance (this=0x4e6db70, index=10, parent=0x4e7bf30, isContextObject=false) at qml/qqmlobjectcreator.cpp:1061
#24 0x00007fe7f08c63ba in QQmlObjectCreator::setPropertyBinding (this=0x4e6db70, property=0x7fe6b41a93b8, binding=0x7fe6b40c5958) at qml/qqmlobjectcreator.cpp:774
#25 0x00007fe7f08c5ef7 in QQmlObjectCreator::setupBindings (this=0x4e6db70, bindingsToSkip=...) at qml/qqmlobjectcreator.cpp:733
#26 0x00007fe7f08c9c4a in QQmlObjectCreator::populateInstance (this=0x4e6db70, index=9, instance=0x4e75050, bindingTarget=0x4e75050, valueTypeProperty=0x0, bindingsToSkip=...) at qml/qqmlobjectcreator.cpp:1348
#27 0x00007fe7f08c8ebb in QQmlObjectCreator::createInstance (this=0x4e6db70, index=9, parent=0x4e75050, isContextObject=false) at qml/qqmlobjectcreator.cpp:1184
#28 0x00007fe7f08c63ba in QQmlObjectCreator::setPropertyBinding (this=0x4e6db70, property=0x7fe6b401b998, binding=0x7fe6b40c5484) at qml/qqmlobjectcreator.cpp:774
#29 0x00007fe7f08c5ef7 in QQmlObjectCreator::setupBindings (this=0x4e6db70, bindingsToSkip=...) at qml/qqmlobjectcreator.cpp:733
#30 0x00007fe7f08c9c4a in QQmlObjectCreator::populateInstance (this=0x4e6db70, index=0, instance=0x0, bindingTarget=0xff4992ecff4992ec, valueTypeProperty=0x0, bindingsToSkip=...) at qml/qqmlobjectcreator.cpp:1348
#31 0x00007fe7f08c8ebb in QQmlObjectCreator::createInstance (this=0x4e6db70, index=0, parent=0x0, isContextObject=true) at qml/qqmlobjectcreator.cpp:1184
#32 0x00007fe7f08c2fe8 in QQmlObjectCreator::create (this=0x4e6db70, subComponentIndex=-1, parent=0x0, interrupt=0x7ffd2ead13f0) at qml/qqmlobjectcreator.cpp:222
#33 0x00007fe7f083a1b2 in QQmlIncubatorPrivate::incubate (this=0x498dfd0, i=...) at qml/qqmlincubator.cpp:302
#34 0x00007fe7f083a73e in QQmlIncubationController::incubateFor (this=0x4a7a4c0, msecs=12) at qml/qqmlincubator.cpp:395
#35 0x00007fe7f261bcc0 in KDeclarative::QmlObjectIncubationController::incubate (this=0x4a7a4b0) at /home/mck182/kf5-dev/build/kdeclarative/src/kdeclarative/../../../../src/kdeclarative/src/kdeclarative/private/qmlobject_p.h:63
#36 0x00007fe7f261bd49 in KDeclarative::QmlObjectIncubationController::incubatingObjectCountChanged (this=0x4a7a4b0, count=1) at /home/mck182/kf5-dev/build/kdeclarative/src/kdeclarative/../../../../src/kdeclarative/src/kdeclarative/private/qmlobject_p.h:79
#37 0x00007fe7f0839933 in QQmlEnginePrivate::incubate (this=0x498e3c0, i=..., forContext=0x4a84080) at qml/qqmlincubator.cpp:97
#38 0x00007fe7f0836296 in QQmlComponent::create (this=0x4e6ad70, incubator=..., context=0x4a7bb00, forContext=0x0) at qml/qqmlcomponent.cpp:1068
#39 0x00007fe7f260aa99 in KDeclarative::QmlObject::completeInitialization (this=0x498dd10, initialProperties=...) at /home/mck182/kf5-dev/src/kdeclarative/src/kdeclarative/qmlobject.cpp:270
#40 0x00007fe7f2f0459e in PlasmaQuick::AppletQuickItem::init (this=0x498d5f0) at /home/mck182/kf5-dev/src/plasma-framework/src/plasmaquick/appletquickitem.cpp:494
#41 0x00007fe7cc208dbd in AppletInterface::init (this=0x498d5f0) at /home/mck182/kf5-dev/src/plasma-framework/src/scriptengines/qml/plasmoid/appletinterface.cpp:175
#42 0x00007fe7cc20b7c0 in AppletInterface::qt_static_metacall (_o=0x498d5f0, _c=QMetaObject::InvokeMetaMethod, _id=22, _a=0x4a7a930) at /home/mck182/kf5-dev/build/plasma-framework/src/scriptengines/qml/moc_appletinterface.cpp:323
#43 0x00007fe7ee8eede7 in QMetaCallEvent::placeMetaCall (this=0x4a7f3b0, object=0x498d5f0) at kernel/qobject.cpp:485
#44 0x00007fe7ee8efeb6 in QObject::event (this=0x498d5f0, e=0x4a7f3b0) at kernel/qobject.cpp:1245
#45 0x00007fe7f3abbf5f in QQuickItem::event (this=0x498d5f0, ev=0x4a7f3b0) at items/qquickitem.cpp:7305
#46 0x00007fe7cc20b283 in AppletInterface::event (this=0x498d5f0, event=0x4a7f3b0) at /home/mck182/kf5-dev/src/plasma-framework/src/scriptengines/qml/plasmoid/appletinterface.cpp:700
#47 0x00007fe7ef3eaffc in QApplicationPrivate::notify_helper (this=0x2294880, receiver=0x498d5f0, e=0x4a7f3b0) at kernel/qapplication.cpp:3722
#48 0x00007fe7ef3e8562 in QApplication::notify (this=0x7ffd2ead2430, receiver=0x498d5f0, e=0x4a7f3b0) at kernel/qapplication.cpp:3164
#49 0x00007fe7ee8b334c in QCoreApplication::notifyInternal (this=0x7ffd2ead2430, receiver=0x498d5f0, event=0x4a7f3b0) at kernel/qcoreapplication.cpp:932
#50 0x00007fe7ee8b6eff in QCoreApplication::sendEvent (receiver=0x498d5f0, event=0x4a7f3b0) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:228
#51 0x00007fe7ee8b4637 in QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x228a2b0) at kernel/qcoreapplication.cpp:1536
#52 0x00007fe7ee8b3fdc in QCoreApplication::sendPostedEvents (receiver=0x0, event_type=0) at kernel/qcoreapplication.cpp:1394
#53 0x00007fe7ee92ba4c in postEventSourceDispatch (s=0x22e76e0) at kernel/qeventdispatcher_glib.cpp:271
#54 0x00007fe7e9ec2c3d in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#55 0x00007fe7e9ec2f20 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#56 0x00007fe7e9ec2fcc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#57 0x00007fe7ee92c1ed in QEventDispatcherGlib::processEvents (this=0x22e8530, flags=...) at kernel/qeventdispatcher_glib.cpp:418
#58 0x00007fe7e084dece in QPAEventDispatcherGlib::processEvents (this=0x22e8530, flags=...) at eventdispatchers/qeventdispatcher_glib.cpp:115
#59 0x00007fe7ee8b0042 in QEventLoop::processEvents (this=0x7ffd2ead22d0, flags=...) at kernel/qeventloop.cpp:128
#60 0x00007fe7ee8b0303 in QEventLoop::exec (this=0x7ffd2ead22d0, flags=...) at kernel/qeventloop.cpp:204
#61 0x00007fe7ee8b3a24 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1185
#62 0x00007fe7eecb1c66 in QGuiApplication::exec () at kernel/qguiapplication.cpp:1532
#63 0x00007fe7ef3e7d83 in QApplication::exec () at kernel/qapplication.cpp:2956
#64 0x000000000046a81c in main (argc=2, argv=0x7ffd2ead2578) at /home/mck182/kf5-dev/src/plasma-workspace/shell/main.cpp:154