I have 1582 reports of this WebKitCookieManager crash affecting gnome-initial-setup, and 9 affecting gnome-control-center, hence I am marking this critical priority. Full backtrace downstream. Version-Release number of selected component: gnome-initial-setup-3.18.0-1.fc23 Additional info: reporter: libreport-2.6.3 backtrace_rating: 4 cmdline: /usr/libexec/gnome-initial-setup --existing-user crash_function: g_type_check_instance_cast executable: /usr/libexec/gnome-initial-setup global_pid: 2709 kernel: 4.2.3-300.fc23.x86_64 runlevel: N 5 type: CCpp uid: 1000 Truncated backtrace: Thread no. 1 (10 frames) #0 g_type_check_instance_cast at gtype.c:4064 #1 cookiesDidChange at /usr/src/debug/webkitgtk-2.10.2/Source/WebKit2/UIProcess/API/gtk/WebKitCookieManager.cpp:132 #2 IPC::callMemberFunctionImpl<WebKit::WebCookieManagerProxy, void (WebKit::WebCookieManagerProxy::*)(), std::tuple<>>(WebKit::WebCookieManagerProxy*, void (WebKit::WebCookieManagerProxy::*)(), std::tuple<>&&, std::index_sequence<>) at /usr/src/debug/webkitgtk-2.10.2/Source/WebKit2/Platform/IPC/HandleMessage.h:16 #3 IPC::callMemberFunction<WebKit::WebCookieManagerProxy, void (WebKit::WebCookieManagerProxy::*)(), std::tuple<>, std::make_index_sequence<0ul> >(std::tuple<>&&, WebKit::WebCookieManagerProxy*, void (WebKit::WebCookieManagerProxy::*)()) at /usr/src/debug/webkitgtk-2.10.2/Source/WebKit2/Platform/IPC/HandleMessage.h:22 #4 IPC::handleMessage<Messages::WebCookieManagerProxy::CookiesDidChange, WebKit::WebCookieManagerProxy, void (WebKit::WebCookieManagerProxy::*)()> at /usr/src/debug/webkitgtk-2.10.2/Source/WebKit2/Platform/IPC/HandleMessage.h:92 #5 WebKit::WebCookieManagerProxy::didReceiveMessage at /usr/src/debug/webkitgtk-2.10.2/x86_64-redhat-linux-gnu/DerivedSources/WebKit2/WebCookieManagerProxyMessageReceiver.cpp:49 #6 IPC::MessageReceiverMap::dispatchMessage at /usr/src/debug/webkitgtk-2.10.2/Source/WebKit2/Platform/IPC/MessageReceiverMap.cpp:102 #7 WebKit::WebProcessPool::dispatchMessage at /usr/src/debug/webkitgtk-2.10.2/Source/WebKit2/UIProcess/WebProcessPool.cpp:1103 #8 WebKit::WebProcessProxy::didReceiveMessage at /usr/src/debug/webkitgtk-2.10.2/Source/WebKit2/UIProcess/WebProcessProxy.cpp:481 #9 IPC::Connection::dispatchMessage at /usr/src/debug/webkitgtk-2.10.2/Source/WebKit2/Platform/IPC/Connection.cpp:903