- If you repeat the steps you described does Plasma crash again in the next boot ?
Thanks
I wonder if this could be related to bug 196207

Yes, plasma crashed again after reboot and login. This time before I was able to type in the kwallet password, so this may be unrelated.

The backtrace however differs a little bit:
Application: Plasma Workspace (kdeinit4), signal: Aborted
__lll_lock_wait_private ()
    at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:91
	in ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S
[Current thread is 1 (Thread 0x7f6f1ea7c750 (LWP 5719))]

Thread 2 (Thread 0x7f6f00409950 (LWP 5722)):
[KCrash Handler]
#5  0x00007f6f1be30d25 in *__GI_raise (sig=<value optimized out>) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
#6  0x00007f6f1be33de1 in *__GI_abort () at abort.c:88
#7  0x00007f6f1be66cf8 in __libc_message (do_abort=2, fmt=0x7f6f1bf19b28 "*** glibc detected *** %s: %s: 0x%s ***\n") at ../sysdeps/unix/sysv/linux/libc_fatal.c:173
#8  0x00007f6f1be706c8 in malloc_printerr (action=2, str=0x7f6f1bf1710d "free(): invalid pointer", ptr=<value optimized out>) at malloc.c:5994
#9  0x00007f6f1be721d6 in *__GI___libc_free (mem=0x7f6f1bf103a0) at malloc.c:3625
#10 0x00007f6f1e5c8742 in QByteArray::operator= (this=0x7f6f1e559d90, other=...) at tools/qbytearray.cpp:851
#11 0x00007f6f1e25acb2 in KCatalogPrivate::setupGettextEnv (this=0x1ddf5d0) at ../../kdecore/localization/kcatalog.cpp:184
#12 0x00007f6f1e25b907 in KCatalog::translateStrict (this=0x1ddf5b0, msgctxt=0x7f6f1e751f20 "QLibrary", msgid=0x7f6f1e73f0e8 "Cannot resolve symbol \"%1\" in %2: %3")
    at ../../kdecore/localization/kcatalog.cpp:257
#13 0x00007f6f1e2702e3 in KLocalePrivate::translate_priv (this=0x1a9a3a0, msgctxt=0x7f6f1e751f20 "QLibrary", msgid=0x7f6f1e73f0e8 "Cannot resolve symbol \"%1\" in %2: %3", msgid_plural=0x0, n=0, 
    language=0x7f6f00408760, translation=0x7f6f00408770) at ../../kdecore/localization/klocale.cpp:817
#14 0x00007f6f1e270e65 in KLocale::translateQt (this=0x1a98fa0, context=0x7f6f1e751f20 "QLibrary", sourceText=0x7f6f1e73f0e8 "Cannot resolve symbol \"%1\" in %2: %3", comment=0x0)
    at ../../kdecore/localization/klocale.cpp:905
#15 0x00007f6f1e1ed54d in KDETranslator::translate (this=<value optimized out>, context=0x7f6f1e751f20 "QLibrary", sourceText=0x7f6f1e73f0e8 "Cannot resolve symbol \"%1\" in %2: %3", message=0x0)
    at ../../kdecore/kernel/kglobal_p.h:52
#16 0x00007f6f1e6c8929 in QTranslator::translate (this=0x165a, context=0x6 <Address 0x6 out of bounds>, sourceText=0xffffffffffffffff <Address 0xffffffffffffffff out of bounds>, 
    disambiguation=0x7f6f1bf103a0 "0123456789abcdefghijklmnopqrstuvwxyz", n=467705424) at kernel/qtranslator.cpp:804
#17 0x00007f6f1e6af999 in QCoreApplication::translate (context=0x7f6f1e751f20 "QLibrary", sourceText=0x7f6f1e73f0e8 "Cannot resolve symbol \"%1\" in %2: %3", disambiguation=0x0, 
    encoding=QCoreApplication::CodecForTr, n=-1) at kernel/qcoreapplication.cpp:1641
#18 0x00007f6f1e6afd6f in QCoreApplication::translate (context=0x165a <Address 0x165a out of bounds>, sourceText=0x6 <Address 0x6 out of bounds>, 
    disambiguation=0xffffffffffffffff <Address 0xffffffffffffffff out of bounds>, encoding=468779936) at kernel/qcoreapplication.cpp:1556
#19 0x00007f6f1e6b2830 in QMetaObject::tr (this=<value optimized out>, s=0x6 <Address 0x6 out of bounds>, c=0xffffffffffffffff <Address 0xffffffffffffffff out of bounds>)
    at kernel/qmetaobject.cpp:314
#20 0x00007f6f1e69f52b in QLibrary::tr (this=0x1d7bc30, symbol=0x7f6f1aa0afbf "res_nclose") at ../../include/QtCore/../../src/corelib/plugin/qlibrary.h:64
#21 QLibraryPrivate::resolve_sys (this=0x1d7bc30, symbol=0x7f6f1aa0afbf "res_nclose") at plugin/qlibrary_unix.cpp:257
#22 0x00007f6f1a9cc7b3 in resolveLibrary () at kernel/qhostinfo_unix.cpp:112
#23 0x00007f6f1a9ccf0a in QHostInfoAgent::fromName (hostName=...) at kernel/qhostinfo_unix.cpp:138
#24 0x00007f6f1a9c2f5e in QHostInfoAgent::run (this=0x1de1120) at kernel/qhostinfo.cpp:289
#25 0x00007f6f1e5c6475 in QThreadPrivate::start (arg=0x1de1120) at thread/qthread_unix.cpp:188
#26 0x00007f6f1b304f9a in start_thread (arg=<value optimized out>) at pthread_create.c:300
#27 0x00007f6f1becb56d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#28 0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f6f1ea7c750 (LWP 5719)):
#0  __lll_lock_wait_private () at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:91
#1  0x00007f6f1be75b1e in _L_lock_3848 () from /lib/libc.so.6
#2  0x00007f6f1be721cb in *__GI___libc_free (mem=0x7f6f1c14ba00) at malloc.c:3623
#3  0x00007f6f1e2689b3 in ~QList (this=0x1a9a3a0) at /usr/include/qt4/QtCore/qlist.h:534
#4  ~QStringList (this=0x1a9a3a0) at /usr/include/qt4/QtCore/qstringlist.h:67
#5  KLocalePrivate::updateCatalogs (this=0x1a9a3a0) at ../../kdecore/localization/klocale.cpp:727
#6  0x00007f6f1e26bd30 in KLocale::insertCatalog (this=0x1a98fa0, catalog=<value optimized out>) at ../../kdecore/localization/klocale.cpp:692
#7  0x00007f6f066f4090 in SM::Net::init (this=0x1dcaee0) at ../../../../plasma/applets/system-monitor/net.cpp:45
#8  0x00007f6f162600d6 in Plasma::Corona::loadLayout (this=0x1b2f6b0, configName=<value optimized out>) at ../../plasma/corona.cpp:377
#9  0x00007f6f16261ab2 in Plasma::Corona::initializeLayout (this=0x1b2f6b0, configName=...) at ../../plasma/corona.cpp:324
#10 0x00007f6f13f5772c in PlasmaApp::corona (this=0x1a580c0) at ../../../../plasma/shells/desktop/plasmaapp.cpp:574
#11 0x00007f6f13f578b8 in PlasmaApp::setupDesktop (this=0x1a580c0) at ../../../../plasma/shells/desktop/plasmaapp.cpp:252
#12 0x00007f6f13f5b9ed in PlasmaApp::qt_metacall (this=0x1a580c0, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fffcaa82e40) at ./plasmaapp.moc:115
#13 0x00007f6f1e6c1682 in QMetaObject::activate (sender=0x1af5870, from_signal_index=<value optimized out>, to_signal_index=4, argv=0xffffffffffffffff) at kernel/qobject.cpp:3112
#14 0x00007f6f1e6c67ef in QSingleShotTimer::timerEvent (this=0x1af5870) at kernel/qtimer.cpp:298
#15 0x00007f6f1e6bbbf3 in QObject::event (this=0x1af5870, e=0x80) at kernel/qobject.cpp:1074
#16 0x00007f6f1c63780d in QApplicationPrivate::notify_helper (this=0x1a61220, receiver=0x1af5870, e=0x7fffcaa83500) at kernel/qapplication.cpp:4056
#17 0x00007f6f1c63f86a in QApplication::notify (this=0x1a580c0, receiver=0x1af5870, e=0x7fffcaa83500) at kernel/qapplication.cpp:4021
#18 0x00007f6f1d29143b in KApplication::notify (this=0x1a580c0, receiver=0x1af5870, event=0x7fffcaa83500) at ../../kdeui/kernel/kapplication.cpp:302
#19 0x00007f6f1e6ac51c in QCoreApplication::notifyInternal (this=0x1a580c0, receiver=0x1af5870, event=0x7fffcaa83500) at kernel/qcoreapplication.cpp:610
#20 0x00007f6f1e6d8826 in QCoreApplication::sendEvent (this=0x1a64850) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:213
#21 QTimerInfoList::activateTimers (this=0x1a64850) at kernel/qeventdispatcher_unix.cpp:572
#22 0x00007f6f1e6d4c9d in timerSourceDispatch (source=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:165
#23 0x00007f6f1b55286a in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#24 0x00007f6f1b555eb8 in ?? () from /usr/lib/libglib-2.0.so.0
#25 0x00007f6f1b55606c in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#26 0x00007f6f1e6d4bff in QEventDispatcherGlib::processEvents (this=0x1a58b20, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:327
#27 0x00007f6f1c6ce64f in QGuiEventDispatcherGlib::processEvents (this=0x7f6f1c14ba00, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:202
#28 0x00007f6f1e6aade2 in QEventLoop::processEvents (this=<value optimized out>, flags=...) at kernel/qeventloop.cpp:149
#29 0x00007f6f1e6ab1b4 in QEventLoop::exec (this=0x7fffcaa837b0, flags=...) at kernel/qeventloop.cpp:201
#30 0x00007f6f1e6ad424 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#31 0x00007f6f13f4226b in kdemain (argc=1, argv=0x1a3c4f0) at ../../../../plasma/shells/desktop/main.cpp:50
#32 0x0000000000407264 in launch (argc=1, _name=0x1a36458 "/usr/bin/plasma-desktop", args=<value optimized out>, cwd=0x0, envc=0, envs=0x1a36478 "", reset_env=false, tty=0x0, avoid_loops=false, 
    startup_id_str=0x40a0ff "0") at ../../kinit/kinit.cpp:677
#33 0x0000000000407a28 in handle_launcher_request (sock=7, who=<value optimized out>) at ../../kinit/kinit.cpp:1169
#34 0x0000000000407fae in handle_requests (waitForPid=0) at ../../kinit/kinit.cpp:1362
#35 0x000000000040863b in main (argc=2, argv=0x7fffcaa84628, envp=0x7fffcaa84640) at ../../kinit/kinit.cpp:1793

I'm wondering if this is related to perhaps incorrect locale setup of this system. For example k3b gives me following error message:

Der Locale-Zeichensatz Ihres Systems ist ANSI_X3.4-1968
Der Locale-Zeichensatz Ihres Systems ist auf ANSI_X3.4-1968 eingestellt. Es ist sehr unwahrscheindlich, dass diese Einstellung bewusst so vorgenommen wurde. Wahrscheinlich wurde gar keine Locale-Einstellung vorgenommen; eine ungültige Einstellung kann zu Problemen beim Erstellen der Projektdaten führen.
Lösung: Für eine Korrekte Locale-Einstellung stellen Sie bitte sicher, dass die LC_*-Umgebungsvariablen festgelegt sind. Normalerweise kümmern sich die Einrichtungsprogramme Ihrer Distribution um diese Einstellung.

Is this german message understandable or should I translate?

FWIW, after disabling compositing this crash disappeared.

*** This bug has been marked as a duplicate of bug 200773 ***

Are you sure this bug is a duplicate of bug 200773?
To me, the backtrace looks completely different.

It would be nice if you could explain a little bit why you think this is a duplicate.

it's true that it's hard to tell, but both seem to end in:
../nptl/sysdeps/unix/sysv/linux/raise.c:64
abort.c:88

so they are probably the same. but since you have a doubt i reopen it, no problem with that (i just try to keep some order in the bugreports, so sometimes errors are made, and this is indeed a hard one to be sure)

This is not bug 200773.  They both ended up in abort.c because they both ended up calling abort(), but it was for different reasons.  200773 was a crash because an unimplemented function was called, this bug is due to memory corruption.

Given that the reporter is on sid with x86_64 I believe this is actually related to bug 196207

Fixed!

*** This bug has been marked as a duplicate of bug 208178 ***