Just installed the proposed upgrade from F22 (I remember the package plasma-desktop in the list), then rebooted and then after the login animation, the crash assistant report a crash from krunner, with the following info:

Application: krunner (krunner), signal: Segmentation fault
Using host libthread_db library "/lib64/libthread_db.so.1".
81	T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
[Current thread is 1 (Thread 0x7f9c1204b900 (LWP 1363))]

Thread 3 (Thread 0x7f9bf1af2700 (LWP 1373)):
#0  0x00007f9c0c14d66d in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f9c0afb0182 in _xcb_conn_wait (__timeout=-1, __nfds=1, __fds=0x7f9bf1af1bc0) at /usr/include/bits/poll2.h:46
#2  0x00007f9c0afb0182 in _xcb_conn_wait (c=c@entry=0x2248a40, cond=cond@entry=0x2248a80, vector=vector@entry=0x0, count=count@entry=0x0) at xcb_conn.c:459
#3  0x00007f9c0afb1cff in xcb_wait_for_event (c=0x2248a40) at xcb_in.c:623
#4  0x00007f9bf3fd75e9 in QXcbEventReader::run() () at /usr/lib64/qt5/plugins/platforms/libqxcb.so
#5  0x00007f9c0cd57ede in QThreadPrivate::start(void*) () at /lib64/libQt5Core.so.5
#6  0x00007f9c08992555 in start_thread (arg=0x7f9bf1af2700) at pthread_create.c:333
#7  0x00007f9c0c158f3d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 2 (Thread 0x7f9bea856700 (LWP 1383)):
#0  0x00007f9c0c14d66d in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f9c07179dbc in g_main_context_iterate.isra () at /lib64/libglib-2.0.so.0
#2  0x00007f9c07179ecc in g_main_context_iteration () at /lib64/libglib-2.0.so.0
#3  0x00007f9c0cf8e75b in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /lib64/libQt5Core.so.5
#4  0x00007f9c0cf34a8a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /lib64/libQt5Core.so.5
#5  0x00007f9c0cd52ff4 in QThread::exec() () at /lib64/libQt5Core.so.5
#6  0x00007f9c1081a935 in QQmlThreadPrivate::run() (this=0x24bfae0) at /usr/src/debug/qtdeclarative-opensource-src-5.4.1/src/qml/qml/ftw/qqmlthread.cpp:141
#7  0x00007f9c0cd57ede in QThreadPrivate::start(void*) () at /lib64/libQt5Core.so.5
#8  0x00007f9c08992555 in start_thread (arg=0x7f9bea856700) at pthread_create.c:333
#9  0x00007f9c0c158f3d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 1 (Thread 0x7f9c1204b900 (LWP 1363)):
[KCrash Handler]
#5  0x00007f9c1079ac80 in QQmlComponent::status() const (this=0x8) at /usr/include/qt5/QtCore/qscopedpointer.h:135
#6  0x00007f9c1079ac80 in QQmlComponent::status() const (p=...) at /usr/include/qt5/QtCore/qglobal.h:961
#7  0x00007f9c1079ac80 in QQmlComponent::status() const (this=0x0) at /usr/src/debug/qtdeclarative-opensource-src-5.4.1/src/qml/qml/qqmlcomponent.h:59
#8  0x00007f9c1079ac80 in QQmlComponent::status() const (this=0x0) at /usr/src/debug/qtdeclarative-opensource-src-5.4.1/src/qml/qml/qqmlcomponent.cpp:422
#9  0x00007f9c11366f1d in KDeclarative::QmlObject::completeInitialization(QHash<QString, QVariant> const&) () at /lib64/libKF5Declarative.so.5
#10 0x0000000000408b2f in View::View(QWindow*) ()
#11 0x0000000000406f3d in main ()


Reproducible: Always

Steps to Reproduce:
I'm not sure is reproducible in the strict terms. If in the next boot I will see it again, I will update this bug report.

Actual Results:  
Crash during startup

Expected Results:  
No crash at all