The assert is reproducible with WebKitBuild/Debug/Source/WebKit2/UIProcess/API/qt/tests/qquickwebview/tst_qquickwebview using Qt5-master (2e1a8b49f437a68e8be5f44351116aa4d9638994). 0x00007ffff76473c9 in WebKit::LayerTreeRenderer::assignImageToLayer (this=0x5fb3d0, layer=0x8b8920, imageID=4294967296) at /home/abecsi/devel/git/webkit-git-svn/Source/WebKit2/UIProcess/CoordinatedGraphics/LayerTreeRenderer.cpp:379 379 ASSERT(it != m_directlyCompositedImages.end()); (gdb) bt #0 0x00007ffff76473c9 in WebKit::LayerTreeRenderer::assignImageToLayer (this=0x5fb3d0, layer=0x8b8920, imageID=4294967296) at /home/abecsi/devel/git/webkit-git-svn/Source/WebKit2/UIProcess/CoordinatedGraphics/LayerTreeRenderer.cpp:379 #1 0x00007ffff764682f in WebKit::LayerTreeRenderer::setLayerState (this=0x5fb3d0, id=17, layerInfo=...) at /home/abecsi/devel/git/webkit-git-svn/Source/WebKit2/UIProcess/CoordinatedGraphics/LayerTreeRenderer.cpp:275 #2 0x00007ffff7644045 in WTF::FunctionWrapper<void (WebKit::LayerTreeRenderer::*)(unsigned int, WebKit::WebLayerInfo const&)>::operator() (this=0x8b44d0, c=0x5fb3d0, p1=17, p2=...) at /home/abecsi/devel/git/webkit-git-svn/Source/WTF/wtf/Functional.h:214 #3 0x00007ffff764352e in WTF::BoundFunctionImpl<WTF::FunctionWrapper<void (WebKit::LayerTreeRenderer::*)(unsigned int, WebKit::WebLayerInfo const&)>, void (WebKit::LayerTreeRenderer*, unsigned int, WebKit::WebLayerInfo)>::operator()() (this= 0x8b44c0) at /home/abecsi/devel/git/webkit-git-svn/Source/WTF/wtf/Functional.h:460 #4 0x00007ffff7648138 in WTF::Function<void ()>::operator()() const (this=0x8b7448) at /home/abecsi/devel/git/webkit-git-svn/Source/WTF/wtf/Functional.h:614 #5 0x00007ffff7647905 in WebKit::LayerTreeRenderer::syncRemoteContent (this=0x5fb3d0) at /home/abecsi/devel/git/webkit-git-svn/Source/WebKit2/UIProcess/CoordinatedGraphics/LayerTreeRenderer.cpp:434 #6 0x00007ffff784ff16 in QQuickWebPage::updatePaintNode (this=0x5c2580, oldNode=0x895910) at /home/abecsi/devel/git/webkit-git-svn/Source/WebKit2/UIProcess/API/qt/qquickwebpage.cpp:90 #7 0x00007fffec2bf33e in QQuickWindowPrivate::updateDirtyNode(QQuickItem*) () from /home/abecsi/devel/git/qt5_build/qtbase/lib/libQtQuick.so.5 #8 0x00007fffec2c03b4 in QQuickWindowPrivate::updateDirtyNodes() () from /home/abecsi/devel/git/qt5_build/qtbase/lib/libQtQuick.so.5 #9 0x00007fffec2c0412 in QQuickWindowPrivate::syncSceneGraph() () from /home/abecsi/devel/git/qt5_build/qtbase/lib/libQtQuick.so.5 #10 0x00007fffec392bb6 in QQuickTrivialWindowManager::renderWindow(QQuickWindow*) () from /home/abecsi/devel/git/qt5_build/qtbase/lib/libQtQuick.so.5 #11 0x00007fffec3933e5 in QQuickTrivialWindowManager::event(QEvent*) () from /home/abecsi/devel/git/qt5_build/qtbase/lib/libQtQuick.so.5 #12 0x00007fffeba5007c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /home/abecsi/devel/git/qt5_build/qtbase/lib/libQtWidgets.so.5 #13 0x00007fffeba53280 in QApplication::notify(QObject*, QEvent*) () from /home/abecsi/devel/git/qt5_build/qtbase/lib/libQtWidgets.so.5 #14 0x00007fffeb0f192e in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /home/abecsi/devel/git/qt5_build/qtbase/lib/libQtCore.so.5 #15 0x00007fffeb0f379e in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /home/abecsi/devel/git/qt5_build/qtbase/lib/libQtCore.so.5 #16 0x00007fffeb138eb3 in postEventSourceDispatch(_GSource*, int (*)(void*), void*) () from /home/abecsi/devel/git/qt5_build/qtbase/lib/libQtCore.so.5 #17 0x00007fffec508475 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0 #18 0x00007fffec5087a8 in ?? () from /usr/lib/libglib-2.0.so.0 #19 0x00007fffec508864 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0 #20 0x00007fffeb13903c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /home/abecsi/devel/git/qt5_build/qtbase/lib/libQtCore.so.5 #21 0x00007fffeb0f1d2c in QCoreApplication::processEvents(QFlags<QEventLoop::ProcessEventsFlag>, int) () from /home/abecsi/devel/git/qt5_build/qtbase/lib/libQtCore.so.5 #22 0x000000000040e12f in QTest::qWait (ms=200) at /home/abecsi/devel/git/qt5_build/qtbase/include/QtTest/../../../../qt5/qtbase/src/testlib/qtestsystem.h:66 #23 0x000000000040ff40 in tst_QQuickWebView::showWebView (this=0x7fffffffe1d0) at /home/abecsi/devel/git/webkit-git-svn/Source/WebKit2/UIProcess/API/qt/tests/qquickwebview/tst_qquickwebview.cpp:269 #24 0x00000000004120be in tst_QQuickWebView::qt_static_metacall (_o=0x7fffffffe1d0, _c=QMetaObject::InvokeMetaMethod, _id=16, _a=0x7fffffffd780) at ./tst_qquickwebview.moc:166 #25 0x00007fffeb0fca2b in QMetaMethod::invoke(QObject*, Qt::ConnectionType, QGenericReturnArgument, QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument) const () from /home/abecsi/devel/git/qt5_build/qtbase/lib/libQtCore.so.5 #26 0x00007fffeb0fd9f3 in QMetaObject::invokeMethod(QObject*, char const*, Qt::ConnectionType, QGenericReturnArgument, QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument) () from /home/abecsi/devel/git/qt5_build/qtbase/lib/libQtCore.so.5 #27 0x00007fffeb6c6ae2 in QTest::qInvokeTestMethod(char const*, char const*) () from /home/abecsi/devel/git/qt5_build/qtbase/lib/libQtTest.so.5 #28 0x00007fffeb6c7742 in QTest::qExec(QObject*, int, char**) () from /home/abecsi/devel/git/qt5_build/qtbase/lib/libQtTest.so.5 #29 0x0000000000411ec8 in main (argc=1, argv=0x7fffffffe2f8) at /home/abecsi/devel/git/webkit-git-svn/Source/WebKit2/UIProcess/API/qt/tests/qquickwebview/tst_qquickwebview.cpp:455