are you using the pre-built package of KDE Neon?

(In reply to Michail Vourlakos from comment #1)
> are you using the pre-built package of KDE Neon?

Yes (0.8.0+p18.04+git20180905.0023-0), I'll try the master branch if that helps

(In reply to TYY331 from comment #2)
> (In reply to Michail Vourlakos from comment #1)
> > are you using the pre-built package of KDE Neon?
> 
> Yes (0.8.0+p18.04+git20180905.0023-0), I'll try the master branch if that
> helps

there is a chance that Latte needs to be rebuilt with new plasma but I will now for sure in a few hours

(In reply to Michail Vourlakos from comment #3)
> (In reply to TYY331 from comment #2)
> > (In reply to Michail Vourlakos from comment #1)
> > > are you using the pre-built package of KDE Neon?
> > 
> > Yes (0.8.0+p18.04+git20180905.0023-0), I'll try the master branch if that
> > helps
> 
> there is a chance that Latte needs to be rebuilt with new plasma but I will
> now for sure in a few hours

I've build the master branch of Latte dock, the problem persists, it shows the same error as with the prepackaged version

(In reply to TYY331 from comment #4)
> (In reply to Michail Vourlakos from comment #3)
> > (In reply to TYY331 from comment #2)
> > > (In reply to Michail Vourlakos from comment #1)
> I've build the master branch of Latte dock, the problem persists, it shows
> the same error as with the prepackaged version

Sorry but I cant confirm the issue... I have just built plasma master branch in a opensuse tumbleweed system and Latte dock from master. It works with no issues in my system. I think that you should report this in Neon bugs list in order to get feedback because it can be a distro specific issue.

Neon dev-stable
Bionic preview
latte-dock 0.8.0+p18.04+git20180916.0816-0

Thread 1 "latte-dock" received signal SIGSEGV, Segmentation fault.
KActivities::Imports::ActivityModel::Private::BackgroundCache::BackgroundCache (this=0x7fffb93f5620 <KActivities::Imports::ActivityModel::Private::backgrounds()::cache>) at ./src/imports/activitymodel.cpp:154
154     ./src/imports/activitymodel.cpp: No such file or directory.
(gdb) bt
#0  KActivities::Imports::ActivityModel::Private::BackgroundCache::BackgroundCache (this=0x7fffb93f5620 <KActivities::Imports::ActivityModel::Private::backgrounds()::cache>) at ./src/imports/activitymodel.cpp:154
#1  KActivities::Imports::ActivityModel::Private::backgrounds () at ./src/imports/activitymodel.cpp:271
#2  KActivities::Imports::ActivityModel::ActivityModel (this=0x555555d35560, parent=<optimised out>) at ./src/imports/activitymodel.cpp:293
#3  0x00007fffb91df1d0 in QQmlPrivate::QQmlElement<KActivities::Imports::ActivityModel>::QQmlElement (this=0x555555d35560) at /usr/include/x86_64-linux-gnu/qt5/QtQml/qqmlprivate.h:98
#4  QQmlPrivate::createInto<KActivities::Imports::ActivityModel> (memory=0x555555d35560) at /usr/include/x86_64-linux-gnu/qt5/QtQml/qqmlprivate.h:107
#5  0x00007ffff56ff772 in QQmlType::create (this=this@entry=0x7fffffffb6c0, out=out@entry=0x7fffffffb6b8, memory=memory@entry=0x7fffffffb6c8, additionalMemory=additionalMemory@entry=144) at qml/qqmlmetatype.cpp:915
#6  0x00007ffff5779106 in QQmlObjectCreator::createInstance (this=this@entry=0x555555c2c900, index=64, parent=0x555555d353c0, isContextObject=isContextObject@entry=false) at qml/qqmlobjectcreator.cpp:1163
#7  0x00007ffff5776f37 in QQmlObjectCreator::setPropertyBinding (this=this@entry=0x555555c2c900, bindingProperty=bindingProperty@entry=0x7fffcc143438, binding=binding@entry=0x7fffd8036db4) at qml/qqmlobjectcreator.cpp:825
#8  0x00007ffff5777a59 in QQmlObjectCreator::setupBindings (this=this@entry=0x555555c2c900, applyDeferredBindings=applyDeferredBindings@entry=false) at qml/qqmlobjectcreator.cpp:777
#9  0x00007ffff5778a16 in QQmlObjectCreator::populateInstance (this=this@entry=0x555555c2c900, index=62, index@entry=63, instance=0x555555d35020, bindingTarget=0x555555d35020, valueTypeProperty=valueTypeProperty@entry=0x0) at qml/qqmlobjectcreator.cpp:1456
#10 0x00007ffff57798e3 in QQmlObjectCreator::createInstance (this=this@entry=0x555555c2c900, index=<optimised out>, parent=<optimised out>, isContextObject=isContextObject@entry=false) at qml/qqmlobjectcreator.cpp:1299
#11 0x00007ffff5776f37 in QQmlObjectCreator::setPropertyBinding (this=this@entry=0x555555c2c900, bindingProperty=bindingProperty@entry=0x7fffcc064668, binding=binding@entry=0x7fffd8036d20) at qml/qqmlobjectcreator.cpp:825
#12 0x00007ffff5777a59 in QQmlObjectCreator::setupBindings (this=this@entry=0x555555c2c900, applyDeferredBindings=applyDeferredBindings@entry=false) at qml/qqmlobjectcreator.cpp:777
#13 0x00007ffff5778a16 in QQmlObjectCreator::populateInstance (this=this@entry=0x555555c2c900, index=0, index@entry=62, instance=0x555555b3cad0, bindingTarget=0x555555b3cad0, valueTypeProperty=valueTypeProperty@entry=0x0) at qml/qqmlobjectcreator.cpp:1456
#14 0x00007ffff57798e3 in QQmlObjectCreator::createInstance (this=this@entry=0x555555c2c900, index=<optimised out>, parent=<optimised out>, isContextObject=isContextObject@entry=false) at qml/qqmlobjectcreator.cpp:1299
#15 0x00007ffff5776f37 in QQmlObjectCreator::setPropertyBinding (this=this@entry=0x555555c2c900, bindingProperty=bindingProperty@entry=0x7fffcc064668, binding=binding@entry=0x7fffd8033d3c) at qml/qqmlobjectcreator.cpp:825
#16 0x00007ffff5777a59 in QQmlObjectCreator::setupBindings (this=this@entry=0x555555c2c900, applyDeferredBindings=applyDeferredBindings@entry=false) at qml/qqmlobjectcreator.cpp:777
#17 0x00007ffff5778a16 in QQmlObjectCreator::populateInstance (this=this@entry=0x555555c2c900, index=-1, index@entry=0, instance=0x0, bindingTarget=0x0, valueTypeProperty=valueTypeProperty@entry=0x0) at qml/qqmlobjectcreator.cpp:1456
#18 0x00007ffff57798e3 in QQmlObjectCreator::createInstance (this=this@entry=0x555555c2c900, index=index@entry=0, parent=parent@entry=0x0, isContextObject=isContextObject@entry=true) at qml/qqmlobjectcreator.cpp:1299
#19 0x00007ffff5779e94 in QQmlObjectCreator::create (this=0x555555c2c900, subComponentIndex=<optimised out>, parent=parent@entry=0x0, interrupt=interrupt@entry=0x7fffffffc700) at qml/qqmlobjectcreator.cpp:203
#20 0x00007ffff56ead47 in QQmlIncubatorPrivate::incubate (this=0x555555a475b0, i=...) at qml/qqmlincubator.cpp:298
#21 0x00007ffff56eb6bc in QQmlEnginePrivate::incubate (this=this@entry=0x5555559a4a30, i=..., forContext=forContext@entry=0x555555a36d90) at qml/qqmlincubator.cpp:89
#22 0x00007ffff56e836c in QQmlComponent::create (this=<optimised out>, incubator=..., context=<optimised out>, forContext=<optimised out>) at qml/qqmlcomponent.cpp:1063
#23 0x00007ffff614e1a5 in KDeclarative::QmlObject::completeInitialization(QHash<QString, QVariant> const&) () from /usr/lib/x86_64-linux-gnu/libKF5Declarative.so.5
#24 0x00007ffff7993882 in PlasmaQuick::AppletQuickItem::init (this=this@entry=0x555555a34e10) at ./src/plasmaquick/appletquickitem.cpp:634
#25 0x00007fffd9b78644 in AppletInterface::init (this=0x555555a34e10) at ./src/scriptengines/qml/plasmoid/appletinterface.cpp:163
#26 0x00007ffff7994de8 in PlasmaQuick::AppletQuickItem::itemChange (this=0x555555a34e10, change=QQuickItem::ItemSceneChange, value=...) at ./src/plasmaquick/appletquickitem.cpp:910
#27 0x00007ffff5cbbc1d in QQuickItemPrivate::itemChange(QQuickItem::ItemChange, QQuickItem::ItemChangeData const&) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#28 0x00007ffff5cc1254 in QQuickItemPrivate::refWindow(QQuickWindow*) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#29 0x00007ffff5cc11fa in QQuickItemPrivate::refWindow(QQuickWindow*) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#30 0x00007ffff5cc2310 in QQuickItem::setParentItem(QQuickItem*) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#31 0x00007ffff79a3d01 in PlasmaQuick::ContainmentViewPrivate::setContainment (this=0x555555ce8610, cont=<optimised out>) at ./src/plasmaquick/containmentview.cpp:138
#32 0x00005555555d731f in Latte::Layout::addDock(Plasma::Containment*, bool, int) ()
#33 0x00005555555d7e48 in Latte::Layout::addContainment(Plasma::Containment*) ()
#34 0x00007ffff26b6bef in QtPrivate::QSlotObjectBase::call (a=0x7fffffffd020, r=0x55555597f100, this=0x55555597a060) at ../../include/QtCore/../../src/corelib/kernel/qobjectdefs_impl.h:376
#35 QMetaObject::activate (sender=0x7fffffffdd70, signalOffset=<optimised out>, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x7fffffffd020) at kernel/qobject.cpp:3754
#36 0x00007ffff26b71a7 in QMetaObject::activate (sender=<optimised out>, m=m@entry=0x7ffff686b140 <Plasma::Corona::staticMetaObject>, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x7fffffffd020) at kernel/qobject.cpp:3633
#37 0x00007ffff65ec05f in Plasma::Corona::containmentAdded (this=<optimised out>, _t1=<optimised out>, _t1@entry=0x55555597a7e0) at ./obj-x86_64-linux-gnu/src/plasma/KF5Plasma_autogen/include/moc_corona.cpp:410
#38 0x00007ffff65ee462 in Plasma::CoronaPrivate::addContainment (this=this@entry=0x555555915320, name=..., args=..., id=id@entry=1, lastScreen=lastScreen@entry=-1, delayedInit=delayedInit@entry=false) at ./src/plasma/corona.cpp:581
#39 0x00007ffff65eefb7 in Plasma::CoronaPrivate::importLayout (this=0x555555915320, conf=..., mergeConfig=mergeConfig@entry=false) at ./src/plasma/corona.cpp:634
#40 0x00007ffff65f0361 in Plasma::Corona::loadLayout (this=0x7fffffffdd70, configName=...) at ./src/plasma/corona.cpp:180
#41 0x00005555555c8252 in Latte::LayoutManager::loadLatteLayout(QString) ()
#42 0x00005555555ca1e3 in ?? ()
#43 0x00007ffff26c3914 in QtPrivate::QSlotObjectBase::call (a=0x7fffffffd540, r=<optimised out>, this=<optimised out>) at ../../include/QtCore/../../src/corelib/kernel/qobjectdefs_impl.h:376
#44 QSingleShotTimer::timerEvent (this=0x555555976b10) at kernel/qtimer.cpp:318
#45 0x00007ffff26b75fb in QObject::event (this=0x555555976b10, e=<optimised out>) at kernel/qobject.cpp:1273
#46 0x00007ffff3414e8c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#47 0x00007ffff341c45f in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#48 0x00007ffff2687ab8 in QCoreApplication::notifyInternal2 (receiver=0x555555976b10, event=event@entry=0x7fffffffd810) at kernel/qcoreapplication.cpp:1048
#49 0x00007ffff26e0f0e in QCoreApplication::sendEvent (event=0x7fffffffd810, receiver=<optimised out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:234
#50 QTimerInfoList::activateTimers (this=0x5555558db840) at kernel/qtimerinfo_unix.cpp:643
#51 0x00007ffff26e16d1 in timerSourceDispatch (source=<optimised out>) at kernel/qeventdispatcher_glib.cpp:182
#52 0x00007fffeb027287 in g_main_context_dispatch () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#53 0x00007fffeb0274c0 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#54 0x00007fffeb02754c in g_main_context_iteration () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#55 0x00007ffff26e1a7f in QEventDispatcherGlib::processEvents (this=0x5555558d3e10, flags=...) at kernel/qeventdispatcher_glib.cpp:423
#56 0x00007fffe598bed1 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5
#57 0x00007ffff2685dea in QEventLoop::exec (this=this@entry=0x7fffffffda80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:214
#58 0x00007ffff268efa0 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1336
#59 0x000055555559c70d in main ()

sorry no idea why it crashes... it points to plasma-frameworks..
as mentioned before, I built Plasma master version and Latte master version in TumbleWeed and it does not crash.

(In reply to Michail Vourlakos from comment #7)
> sorry no idea why it crashes... it points to plasma-frameworks..
> as mentioned before, I built Plasma master version and Latte master version
> in TumbleWeed and it does not crash.

Well, after retrying likely frameworks builds that had failed yesterday, and doing an update, latte seems to run now in a 18.04 VM.

If the reporter can confirm that, then I guess this was likely just a case of dependant builds getting out of sync due to a temp builder problem.

(In reply to Rik Mills from comment #8)
> (In reply to Michail Vourlakos from comment #7)
> If the reporter can confirm that, then I guess this was likely just a case
> of dependant builds getting out of sync due to a temp builder problem.

makes sense

After a recent update in the dev stable channel I can confirm Latte Dock is working again, no crashes or problems so far