Fresh install from Kubuntu (16) DVD, local settings Germany/german, always updated packages incl kernels.
Since the beginning systemsettings crash on close, this is a typical 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 0x7f6664b398c0 (LWP 6955))]

Thread 3 (Thread 0x7f66297f8700 (LWP 7054)):
#0  syscall () at ../sysdeps/unix/sysv/linux/x86_64/syscall.S:38
#1  0x00007f665e1edd4a in g_cond_wait_until () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f665e17d999 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f665e17dfbb in g_async_queue_timeout_pop () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007f665e1d061a in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007f665e1cfbc5 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#6  0x00007f665e6ca6ba in start_thread (arg=0x7f66297f8700) at pthread_create.c:333
#7  0x00007f666126482d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 2 (Thread 0x7f66531fa700 (LWP 6956)):
#0  0x00007f6661258b5d in poll () at ../sysdeps/unix/syscall-template.S:84
#1  0x00007f665ef40c62 in ?? () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#2  0x00007f665ef428d7 in xcb_wait_for_event () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#3  0x00007f665554c629 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5
#4  0x00007f666194e7be in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007f665e6ca6ba in start_thread (arg=0x7f66531fa700) at pthread_create.c:333
#6  0x00007f666126482d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 1 (Thread 0x7f6664b398c0 (LWP 6955)):
[KCrash Handler]
#6  0x00007f6661b376e3 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#7  0x00007f6661b620cb in QObject::disconnect(QObject const*, char const*, QObject const*, char const*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#8  0x00007f6644ce41b3 in KParts::PartManager::~PartManager() () from /usr/lib/x86_64-linux-gnu/libKF5Parts.so.5
#9  0x00007f6644ce4369 in KParts::PartManager::~PartManager() () from /usr/lib/x86_64-linux-gnu/libKF5Parts.so.5
#10 0x00007f6661b5c28b in QObjectPrivate::deleteChildren() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#11 0x00007f6661b65b00 in QObject::~QObject() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#12 0x00007f664542731b in KHTMLPart::~KHTMLPart() () from /usr/lib/x86_64-linux-gnu/libKF5KHtml.so.5
#13 0x00007f6645427439 in KHTMLPart::~KHTMLPart() () from /usr/lib/x86_64-linux-gnu/libKF5KHtml.so.5
#14 0x00007f6661b5ec20 in QObject::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#15 0x00007f666300205c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#16 0x00007f6663007516 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#17 0x00007f6661b2f38b in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#18 0x00007f6661b31786 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#19 0x00007f6661b853c3 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#20 0x00007f665e1a91a7 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#21 0x00007f665e1a9400 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#22 0x00007f665e1a94ac in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#23 0x00007f6661b857cf in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#24 0x00007f6661b2cb4a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#25 0x00007f6661b34bec in QCoreApplication::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#26 0x000000000040f7a1 in main ()