Application: umbrello (2.4.2)
KDE Platform Version: 4.4.2 (KDE 4.4.2)
Qt Version: 4.6.2
Operating System: Linux 2.6.32-21-generic x86_64
Distribution: Ubuntu 10.04 LTS

-- Information about the crash:
I see that crashes in Umbrello during undo have already been reported, but hopefully this backtrace will add a little more light.

What happened: I was working with a relatively simple class diagram, involving 2 boxes, 2 labels, about 14 classes, and about 6 packages.  Having accidentally deleted a box rather than an association, I pressed undo.  Nothing happened in the diagram.  I noticed the undo history seemed to be changing in the middle of the history, rather than at the bottom or top.  Pressed undo a few more times, no diagram change for about 6 goes, then stuff I did much earlier began to disappear as I kept pressing undo.  Switched to redo, and it crashed immediately on the first redo.

It may or may not be related, but prior to this, I had noticed that clicking the dependency toolbar button had no effect for a few clicks (button seemed non-responsive), then suddenly worked with no actions taken to fix it.  Computer was not lagging.

 -- Backtrace:
Application: Umbrello UML Modeller (umbrello), signal: Segmentation fault
[Current thread is 1 (Thread 0x7ffd13c90760 (LWP 3378))]

Thread 2 (Thread 0x7ffcfccc5710 (LWP 3476)):
#0  0x00007ffd0f897f53 in *__GI___poll (fds=<value optimized out>, nfds=<value optimized out>, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:87
#1  0x00007ffd0c3d04a9 in ?? () from /lib/libglib-2.0.so.0
#2  0x00007ffd0c3d08fc in g_main_context_iteration () from /lib/libglib-2.0.so.0
#3  0x00007ffd10ba3566 in QEventDispatcherGlib::processEvents (this=0x20373d0, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:414
#4  0x00007ffd10b78992 in QEventLoop::processEvents (this=<value optimized out>, flags=) at kernel/qeventloop.cpp:149
#5  0x00007ffd10b78d6c in QEventLoop::exec (this=0x7ffcfccc4db0, flags=) at kernel/qeventloop.cpp:201
#6  0x00007ffd10a82d59 in QThread::exec (this=<value optimized out>) at thread/qthread.cpp:487
#7  0x00007ffd10b59178 in QInotifyFileSystemWatcherEngine::run (this=0x202e6c0) at io/qfilesystemwatcher_inotify.cpp:248
#8  0x00007ffd10a85775 in QThreadPrivate::start (arg=0x202e6c0) at thread/qthread_unix.cpp:248
#9  0x00007ffd107f59ca in start_thread (arg=<value optimized out>) at pthread_create.c:300
#10 0x00007ffd0f8a469d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#11 0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7ffd13c90760 (LWP 3378)):
[KCrash Handler]
#5  QBasicAtomicInt::ref (this=0x1cd5820) at ../../include/QtCore/../../src/corelib/arch/qatomic_x86_64.h:121
#6  QString (this=0x1cd5820) at ../../include/QtCore/../../src/corelib/tools/qstring.h:715
#7  QUndoCommand::text (this=0x1cd5820) at util/qundostack.cpp:241
#8  0x00007ffd116cca2f in QUndoStack::undoText (this=<value optimized out>) at util/qundostack.cpp:795
#9  0x00007ffd116cda77 in QUndoStackPrivate::setIndex (this=0x1bc43c0, idx=<value optimized out>, clean=false) at util/qundostack.cpp:401
#10 0x00007ffd116f1328 in QUndoStack::qt_metacall (this=0x1bc3ec0, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fff7b48e760) at .moc/release-shared/moc_qundostack.cpp:106
#11 0x00007ffd10b8ce3f in QMetaObject::activate (sender=0x1bd7d50, m=<value optimized out>, local_signal_index=<value optimized out>, argv=0x25f2d70) at kernel/qobject.cpp:3293
#12 0x00007ffd11047032 in QAction::triggered (this=0x7fff7b48e5f0, _t1=false) at .moc/release-shared/moc_qaction.cpp:263
#13 0x00007ffd110490ab in QAction::activate (this=0x1bd7d50, event=<value optimized out>) at kernel/qaction.cpp:1255
#14 0x00007ffd1148839d in QMenuPrivate::activateCausedStack (this=<value optimized out>, causedStack=..., action=0x1bd7d50, action_e=QAction::Trigger, self=true) at widgets/qmenu.cpp:1011
#15 0x00007ffd1148ddda in QMenuPrivate::activateAction (this=0x1f06b00, action=0x1bd7d50, action_e=QAction::Trigger, self=<value optimized out>) at widgets/qmenu.cpp:1103
#16 0x00007ffd12530cee in KMenu::mouseReleaseEvent (this=0x1c3d200, e=0x1cd5820) at ../../kdeui/widgets/kmenu.cpp:471
#17 0x00007ffd110a3582 in QWidget::event (this=0x1c3d200, event=0x7fff7b48f3b0) at kernel/qwidget.cpp:7998
#18 0x00007ffd1148ff9b in QMenu::event (this=0x1c3d200, e=0x7fff7b48f3b0) at widgets/qmenu.cpp:2414
#19 0x00007ffd1104d22c in QApplicationPrivate::notify_helper (this=0x19dbed0, receiver=0x1c3d200, e=0x7fff7b48f3b0) at kernel/qapplication.cpp:4300
#20 0x00007ffd11053ecb in QApplication::notify (this=0x7fff7b4900c0, receiver=0x1c3d200, e=0x7fff7b48f3b0) at kernel/qapplication.cpp:3865
#21 0x00007ffd12454526 in KApplication::notify (this=0x7fff7b4900c0, receiver=0x1c3d200, event=0x7fff7b48f3b0) at ../../kdeui/kernel/kapplication.cpp:302
#22 0x00007ffd10b7a06c in QCoreApplication::notifyInternal (this=0x7fff7b4900c0, receiver=0x1c3d200, event=0x7fff7b48f3b0) at kernel/qcoreapplication.cpp:704
#23 0x00007ffd110530ae in QCoreApplication::sendEvent (receiver=0x1c3d200, event=0x7fff7b48f3b0, alienWidget=0x0, nativeWidget=0x1c3d200, buttonDown=<value optimized out>, 
    lastMouseReceiver=<value optimized out>, spontaneous=true) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:215
#24 QApplicationPrivate::sendMouseEvent (receiver=0x1c3d200, event=0x7fff7b48f3b0, alienWidget=0x0, nativeWidget=0x1c3d200, buttonDown=<value optimized out>, lastMouseReceiver=<value optimized out>, 
    spontaneous=true) at kernel/qapplication.cpp:2965
#25 0x00007ffd110d33dd in QETWidget::translateMouseEvent (this=0x1c3d200, event=<value optimized out>) at kernel/qapplication_x11.cpp:4302
#26 0x00007ffd110d18ac in QApplication::x11ProcessEvent (this=<value optimized out>, event=0x7fff7b48fcd0) at kernel/qapplication_x11.cpp:3501
#27 0x00007ffd110fd882 in x11EventSourceDispatch (s=0x19dfc30, callback=<value optimized out>, user_data=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:146
#28 0x00007ffd0c3cc8c2 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#29 0x00007ffd0c3d0748 in ?? () from /lib/libglib-2.0.so.0
#30 0x00007ffd0c3d08fc in g_main_context_iteration () from /lib/libglib-2.0.so.0
#31 0x00007ffd10ba3513 in QEventDispatcherGlib::processEvents (this=0x19b47c0, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:412
#32 0x00007ffd110fd46e in QGuiEventDispatcherGlib::processEvents (this=0x7fff7b48e5f0, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:204
#33 0x00007ffd10b78992 in QEventLoop::processEvents (this=<value optimized out>, flags=) at kernel/qeventloop.cpp:149
#34 0x00007ffd10b78d6c in QEventLoop::exec (this=0x7fff7b490000, flags=) at kernel/qeventloop.cpp:201
#35 0x00007ffd10b7caab in QCoreApplication::exec () at kernel/qcoreapplication.cpp:981
#36 0x0000000000b6c6c5 in main (argc=<value optimized out>, argv=<value optimized out>) at ../../../umbrello/umbrello/main.cpp:111

This bug may be a duplicate of or related to bug 207690.

Possible duplicates by query: bug 229635, bug 214309.

Reported using DrKonqi