Seen while running Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; en-US; rv:2.0b2pre) Gecko/20100713 Minefield/4.0b2pre My crash report is: http://crash-stats.mozilla.com/report/index/bp-e0ebf12b-8cfc-4b15-b9e1-dcc332100713. Confirm that this works using Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.6) Gecko/20100625 Firefox/3.6.6 as well as Beta 1 so it is a regression. STR: 1. Load site in URL. 2. Crash. Frame Module Signature [Expand] Source 0 XUL nsHTMLCanvasElement::GetContext nsISupportsUtils.h:184 1 XUL nsIDOMHTMLCanvasElement_GetContext dom_quickstubs.cpp:17439 2 libmozjs.dylib js_Interpret js/src/jsops.cpp:2148 3 libmozjs.dylib js_Invoke js/src/jsinterp.cpp:664 4 libmozjs.dylib js_InternalInvoke js/src/jsinterp.cpp:694 5 libmozjs.dylib JS_CallFunctionValue js/src/jsapi.cpp:4632 6 XUL nsJSContext::CallEventHandler dom/base/nsJSEnvironment.cpp:2204 7 XUL nsJSEventListener::HandleEvent dom/src/events/nsJSEventListener.cpp:228 8 XUL nsEventListenerManager::HandleEventSubType content/events/src/nsEventListenerManager.cpp:1094 9 XUL nsEventListenerManager::HandleEventInternal content/events/src/nsEventListenerManager.cpp:1190 10 XUL nsEventTargetChainItem::HandleEventTargetChain content/events/src/nsEventListenerManager.h:146 11 XUL nsEventDispatcher::Dispatch content/events/src/nsEventDispatcher.cpp:628 12 XUL DocumentViewerImpl::LoadComplete layout/base/nsDocumentViewer.cpp:1037 13 XUL nsDocShell::EndPageLoad docshell/base/nsDocShell.cpp:5766 14 XUL nsDocShell::OnStateChange docshell/base/nsDocShell.cpp:5647 15 XUL nsDocLoader::FireOnStateChange uriloader/base/nsDocLoader.cpp:1321 16 XUL nsDocLoader::DocLoaderIsEmpty uriloader/base/nsDocLoader.cpp:929 17 XUL nsDocLoader::OnStopRequest uriloader/base/nsDocLoader.cpp:700 18 XUL nsLoadGroup::RemoveRequest netwerk/base/src/nsLoadGroup.cpp:680 19 XUL nsDocument::DoUnblockOnload content/base/src/nsDocument.cpp:6945 20 XUL nsLoadBlockingPLDOMEvent::~nsLoadBlockingPLDOMEvent content/events/src/nsPLDOMEvent.cpp:86 21 XUL nsRunnable::Release nsThreadUtils.cpp:55 22 XUL nsCOMPtr_base::~nsCOMPtr_base nsCOMPtr.cpp:81 23 XUL nsThread::ProcessNextEvent 24 XUL NS_ProcessPendingEvents_P nsThreadUtils.cpp:200 25 XUL nsBaseAppShell::NativeEventCallback widget/src/xpwidgets/nsBaseAppShell.cpp:126 26 XUL nsAppShell::ProcessGeckoEvents widget/src/cocoa/nsAppShell.mm:394 27 CoreFoundation __CFRunLoopDoSources0 28 CoreFoundation __CFRunLoopRun 29 CoreFoundation CFRunLoopRunSpecific 30 CoreFoundation CFRunLoopRunInMode 31 HIToolbox RunCurrentEventLoopInMode 32 HIToolbox ReceiveNextEventCommon 33 HIToolbox BlockUntilNextEventMatchingListInMode 34 AppKit _DPSNextEvent 35 AppKit -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] 36 AppKit -[NSApplication run] 37 XUL nsAppShell::Run widget/src/cocoa/nsAppShell.mm:747 38 XUL nsAppStartup::Run toolkit/components/startup/src/nsAppStartup.cpp:192 39 XUL XRE_main toolkit/xre/nsAppRunner.cpp:3619 40 firefox-bin main browser/app/nsBrowserApp.cpp:158 41 firefox-bin firefox-bin@0xbf5 42 @0x2

These crashes started in today's nightly. Regression range: Works in Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; en-US; rv:2.0b2pre) Gecko/20100712 Minefield/4.0b2pre Broken in Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; en-US; rv:2.0b2pre) Gecko/20100713 Minefield/4.0b2pre http://tinyurl.com/296t9lm links to the checkins. Could Bug 401788 be implicated?

Yeah.