1) Go to washingtonpost.com (or any sufficiently complex site, google won't work), let it load completely 2) Go to some article page, let it load completely 3) Start going quickly back-forward between the front page and article page (command-[ and ] makes this easy) 4) Eventually you will hit the following assertion: ASSERTION FAILED: dataSource (/Users/antti/src/webkit/trunk/WebKit/WebView/WebHTMLView.mm:3094 -[WebHTMLView setDataSource:]) Thread 0 Crashed: 0 com.apple.WebKit 0x0033cd01 -[WebHTMLView setDataSource:] + 67 (WebHTMLView.mm:3094) 1 com.apple.WebKit 0x003910ea WebFrameLoaderClient::setDocumentViewFromPageCache(WebCore::PageCache*) + 196 (WebFrameLoaderClient.mm:181) 2 com.apple.WebCore 0x013c6e76 WebCore::FrameLoader::transitionToCommitted(WTF::PassRefPtr<WebCore::PageCache>) + 494 (FrameLoader.cpp:2360) 3 com.apple.WebCore 0x013c7536 WebCore::FrameLoader::commitProvisionalLoad(WTF::PassRefPtr<WebCore::PageCache>) + 190 (FrameLoader.cpp:2293) 4 com.apple.WebCore 0x013cad3d WebCore::DocumentLoader::loadFromPageCache(WTF::PassRefPtr<WebCore::PageCache>) + 101 (DocumentLoader.cpp:523) 5 com.apple.WebCore 0x013bd7fa WebCore::FrameLoader::loadProvisionalItemFromPageCache() + 224 (FrameLoader.cpp:3508) 6 com.apple.WebCore 0x013c1b0f WebCore::FrameLoader::continueLoadAfterNavigationPolicy(WebCore::ResourceRequest const&, WTF::PassRefPtr<WebCore::FormState>, bool) + 639 (FrameLoader.cpp:3371) 7 com.apple.WebCore 0x013c1c04 WebCore::FrameLoader::callContinueLoadAfterNavigationPolicy(void*, WebCore::ResourceRequest const&, WTF::PassRefPtr<WebCore::FormState>, bool) + 70 (FrameLoader.cpp:3325) 8 com.apple.WebCore 0x013be1a7 WebCore::PolicyCheck::call(bool) + 109 (FrameLoader.cpp:4208) 9 com.apple.WebCore 0x013c1628 WebCore::FrameLoader::continueAfterNavigationPolicy(WebCore::PolicyAction) + 388 (FrameLoader.cpp:3318) 10 com.apple.WebKit 0x00394ba7 WebFrameLoaderClient::receivedPolicyDecison(WebCore::PolicyAction) + 297 (WebFrameLoaderClient.mm:1013) 11 com.apple.WebKit 0x003953b5 -[WebFramePolicyListener receivedPolicyDecision:] + 133 (WebFrameLoaderClient.mm:1198) 12 com.apple.WebKit 0x00394615 -[WebFramePolicyListener use] + 43 (WebFrameLoaderClient.mm:1214) 13 libobjc.A.dylib 0x90a57c56 objc_msgSendv + 54 14 com.apple.Foundation 0x925fc43e -[NSInvocation invoke] + 932 15 com.apple.Foundation 0x92622433 -[NSInvocation invokeWithTarget:] + 67 16 com.apple.WebKit 0x0035efce -[_WebSafeForwarder forwardInvocation:] + 448 (WebView.mm:1443) 17 com.apple.Foundation 0x925fb4f4 -[NSObject(NSForwardInvocation) forward::] + 469 18 libobjc.A.dylib 0x90a57ba1 _objc_msgForward + 49 19 com.apple.WebKit 0x00394de8 WebFrameLoaderClient::dispatchDecidePolicyForNavigationAction(void (WebCore::FrameLoader::*)(WebCore::PolicyAction), WebCore::NavigationAction const&, WebCore::ResourceRequest const&) + 212 (WebFrameLoaderClient.mm:528) 20 com.apple.WebCore 0x013c1165 WebCore::FrameLoader::checkNavigationPolicy(WebCore::ResourceRequest const&, WebCore::DocumentLoader*, WTF::PassRefPtr<WebCore::FormState>, void (*)(void*, WebCore::ResourceRequest const&, WTF::PassRefPtr<WebCore::FormState>, bool), void*) + 675 (FrameLoader.cpp:3292) 21 com.apple.WebCore 0x013c26f9 WebCore::FrameLoader::load(WebCore::DocumentLoader*, WebCore::FrameLoadType, WTF::PassRefPtr<WebCore::FormState>) + 389 (FrameLoader.cpp:1892) 22 com.apple.WebCore 0x013c2aeb WebCore::FrameLoader::load(WebCore::ResourceRequest const&, WebCore::NavigationAction const&, WebCore::FrameLoadType, WTF::PassRefPtr<WebCore::FormState>) + 293 (FrameLoader.cpp:1842) 23 com.apple.WebCore 0x013c599b WebCore::FrameLoader::loadItem(WebCore::HistoryItem*, WebCore::FrameLoadType) + 1847 (FrameLoader.cpp:3829) 24 com.apple.WebCore 0x013c5e2b WebCore::FrameLoader::recursiveGoToItem(WebCore::HistoryItem*, WebCore::HistoryItem*, WebCore::FrameLoadType) + 1065 (FrameLoader.cpp:3927) 25 com.apple.WebCore 0x013c5f19 WebCore::FrameLoader::goToItem(WebCore::HistoryItem*, WebCore::FrameLoadType) + 205 (FrameLoader.cpp:3874) 26 com.apple.WebCore 0x011a4a70 WebCore::Page::goToItem(WebCore::HistoryItem*, WebCore::FrameLoadType) + 308 (Page.cpp:139) 27 com.apple.WebCore 0x011a4ab7 WebCore::Page::goForward() + 63 (Page.cpp:126) 28 com.apple.WebKit 0x003615c3 -[WebView goForward] + 23 (WebView.mm:1978) 29 com.apple.WebKit 0x00359013 -[WebFrameView _goForward] + 57 (WebFrameView.mm:556) 30 com.apple.WebKit 0x0035a346 -[WebFrameView keyDown:] + 2394 (WebFrameView.mm:832) 31 com.apple.AppKit 0x932e2b59 forwardMethod + 82 32 com.apple.AppKit 0x932e2b59 forwardMethod + 82 33 com.apple.AppKit 0x932e2b59 forwardMethod + 82 34 com.apple.AppKit 0x934383a1 -[NSControl keyDown:] + 122 35 com.apple.WebKit 0x0033db10 -[WebHTMLView keyDown:] + 462 (WebHTMLView.mm:3356) 36 com.apple.AppKit 0x9334cbe1 -[NSWindow sendEvent:] + 7377 37 com.apple.Safari 0x00022cd2 0x1000 + 138450 38 com.apple.AppKit 0x9333e350 -[NSApplication sendEvent:] + 5023 39 com.apple.Safari 0x00022862 0x1000 + 137314 40 com.apple.AppKit 0x93268dfe -[NSApplication run] + 547 41 com.apple.AppKit 0x9325cd2f NSApplicationMain + 573 42 com.apple.Safari 0x0005ef22 0x1000 + 384802 43 com.apple.Safari 0x0005ee3d 0x1000 + 384573
May be a duplicate of or related to Bug 12664.