By the way the original video is https://files.mstdn.plus/media_attachments/files/109/741/370/830/109/352/original/11efc48252259f8c.mp4

I found another example: the YouTube video https://hachyderm.io/@mikeymikey/109758095653559893 on the timeline https://hachyderm.io/@mikeymikey Again, the bug only occurs if you use the timeline rather than the direct post link. You can try to enter full screen from the YouTube full screen widget.

<rdar://problem/104720138>

Looks like this assertion is there since 2012 at least: ASSERT(m_element); if (!m_element) return;

I can reproduce a crash with https://hachyderm.io/@mikeymikey/117106856897792159 but the backtrace seems quite different: https://searchfox.org/wubkat/rev/b934faaa9c958fb3278550542b2eb3b127e363f2/Source/WebCore/page/LocalFrameViewLayoutContext.cpp#97

Complete backtrace: #0 0x0000007000002920 in WTFCrashWithInfo at /Users/fred/WebKit/WebKitBuild/Debug/usr/local/include/wtf/Assertions.h:1140 #1 0x00000070042ab2c0 in WebCore::RenderTreeNeedsLayoutChecker::~RenderTreeNeedsLayoutChecker()::'lambda'(WebCore::RenderObject const&)::operator()(WebCore::RenderObject const&) const at /Users/fred/WebKit/Source/WebCore/page/LocalFrameViewLayoutContext.cpp:97 #2 0x00000070042ab1f0 in WebCore::RenderTreeNeedsLayoutChecker::~RenderTreeNeedsLayoutChecker at /Users/fred/WebKit/Source/WebCore/page/LocalFrameViewLayoutContext.cpp:104 #3 0x000000700424f3c0 in WebCore::RenderTreeNeedsLayoutChecker::~RenderTreeNeedsLayoutChecker at /Users/fred/WebKit/Source/WebCore/page/LocalFrameViewLayoutContext.cpp:84 #4 0x000000700424e648 in WebCore::LocalFrameViewLayoutContext::performLayout at /Users/fred/WebKit/Source/WebCore/page/LocalFrameViewLayoutContext.cpp:312 #5 0x000000700424eb7c in WebCore::LocalFrameViewLayoutContext::interleavedLayout at /Users/fred/WebKit/Source/WebCore/page/LocalFrameViewLayoutContext.cpp:200 #6 0x000000700178733c in WebCore::Document::resolveStyle at /Users/fred/WebKit/Source/WebCore/dom/Document.cpp:2921 #7 0x00000070017885e4 in WebCore::Document::updateStyleIfNeeded at /Users/fred/WebKit/Source/WebCore/dom/Document.cpp:3077 #8 0x0000007001788b14 in WebCore::Document::updateLayout at /Users/fred/WebKit/Source/WebCore/dom/Document.cpp:3156 #9 0x0000007001788ac0 in WebCore::Document::updateLayout at /Users/fred/WebKit/Source/WebCore/dom/Document.cpp:3152 #10 0x000000011e3fb898 in WebKit::WebFullScreenManager::willEnterFullScreen at /Users/fred/WebKit/Source/WebKit/WebProcess/FullScreen/WebFullScreenManager.cpp:594 #11 0x000000011e421a04 in WebKit::WebFullScreenManager::performEnterFullScreen()::$_2::operator()(bool) at /Users/fred/WebKit/Source/WebKit/WebProcess/FullScreen/WebFullScreenManager.cpp:507 #12 0x000000011e421984 in std::__1::__invoke[abi:sqn220106]<WebKit::WebFullScreenManager::performEnterFullScreen()::$_2, bool> at /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX27.0.sdk/usr/include/c++/v1/__type_traits/invoke.h:90 #13 0x000000011e421950 in std::__1::__apply_tuple_impl[abi:sqn220106]<WebKit::WebFullScreenManager::performEnterFullScreen()::$_2, std::__1::tuple<bool>, 0ul> at /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX27.0.sdk/usr/include/c++/v1/tuple:1397 #14 0x000000011e421914 in std::__1::apply[abi:sqn220106]<WebKit::WebFullScreenManager::performEnterFullScreen()::$_2, std::__1::tuple<bool>> at /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX27.0.sdk/usr/include/c++/v1/tuple:1401 #15 0x000000011e42187c in IPC::Connection::callReply<Messages::WebFullScreenManagerProxy::EnterFullScreen, WebKit::WebFullScreenManager::performEnterFullScreen()::$_2> at /Users/fred/WebKit/Source/WebKit/Platform/IPC/Connection.h:1164 #16 0x000000011e4217a0 in WTF::CompletionHandler<void (IPC::Connection*, IPC::Decoder*)> IPC::Connection::makeAsyncReplyCompletionHandler<Messages::WebFullScreenManagerProxy::EnterFullScreen, WebKit::WebFullScreenManager::performEnterFullScreen()::$_2>(WebKit::WebFullScreenManager::performEnterFullScreen()::$_2&&, WTF::ThreadLikeAssertion)::'lambda'(IPC::Connection*, IPC::Decoder*)::operator()(IPC::Connection*, IPC::Decoder*) at /Users/fred/WebKit/Source/WebKit/Platform/IPC/Connection.h:1075 #17 0x000000011e421650 in WTF::Detail::CallableWrapper<WTF::CompletionHandler<void (IPC::Connection*, IPC::Decoder*)> IPC::Connection::makeAsyncReplyCompletionHandler<Messages::WebFullScreenManagerProxy::EnterFullScreen, WebKit::WebFullScreenManager::performEnterFullScreen()::$_2>(WebKit::WebFullScreenManager::performEnterFullScreen()::$_2&&, WTF::ThreadLikeAssertion)::'lambda'(IPC::Connection*, IPC::Decoder*), void, IPC::Connection*, IPC::Decoder*>::call at /Users/fred/WebKit/WebKitBuild/Debug/usr/local/include/wtf/Function.h:59 #18 0x000000011d2c2a38 in WTF::Function<void (IPC::Connection*, IPC::Decoder*)>::operator() at /Users/fred/WebKit/WebKitBuild/Debug/usr/local/include/wtf/Function.h:103 #19 0x000000011d29dfe8 in WTF::CompletionHandler<void (IPC::Connection*, IPC::Decoder*)>::operator() at /Users/fred/WebKit/WebKitBuild/Debug/usr/local/include/wtf/CompletionHandler.h:110 #20 0x000000011f1a6050 in IPC::Connection::dispatchMessage at /Users/fred/WebKit/Source/WebKit/Platform/IPC/Connection.cpp:1424 #21 0x000000011f1a6700 in IPC::Connection::dispatchMessage at /Users/fred/WebKit/Source/WebKit/Platform/IPC/Connection.cpp:1499 #22 0x000000011f1a6b40 in IPC::Connection::dispatchOneIncomingMessage at /Users/fred/WebKit/Source/WebKit/Platform/IPC/Connection.cpp:1567 #23 0x000000011f1cbf14 in IPC::Connection::enqueueIncomingMessage(WTF::UniqueRef<IPC::Decoder>)::$_1::operator()() const at /Users/fred/WebKit/Source/WebKit/Platform/IPC/Connection.cpp:1403 #24 0x000000011f1cbe70 in WTF::Detail::CallableWrapper<IPC::Connection::enqueueIncomingMessage(WTF::UniqueRef<IPC::Decoder>)::$_1, void>::call at /Users/fred/WebKit/WebKitBuild/Debug/usr/local/include/wtf/Function.h:59 #25 0x000000013371d9f4 in WTF::Function<void ()>::operator() at /Users/fred/WebKit/WebKitBuild/Debug/usr/local/include/wtf/Function.h:103 #26 0x0000000130ffb544 in WTF::RunLoop::performWork at /Users/fred/WebKit/Source/WTF/wtf/RunLoop.cpp:146 #27 0x0000000131002ff4 in WTF::RunLoop::performWork at /Users/fred/WebKit/Source/WTF/wtf/cf/RunLoopCF.cpp:44 #28 0x00000001835e6944 in __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ () #29 0x00000001835e68d8 in __CFRunLoopDoSource0 () #30 0x00000001835e6610 in __CFRunLoopDoSources0 () #31 0x00000001835e51e0 in __CFRunLoopRun () #32 0x00000001836bf82c in _CFRunLoopRunSpecificWithOptions () #33 0x0000000184ce8d5c in -[NSRunLoop(NSRunLoop) runMode:beforeDate:] () #34 0x0000000184d61bcc in -[NSRunLoop(NSRunLoop) run] () #35 0x00000001831fc524 in _xpc_objc_main () #36 0x0000000183210074 in _xpc_main () #37 0x00000001831fbf64 in xpc_main () #38 0x000000011be95b78 in WebKit::XPCServiceMain at /Users/fred/WebKit/Source/WebKit/Shared/EntryPointUtilities/Cocoa/XPCService/XPCServiceMain.mm:314 #39 0x000000011f087084 in WKXPCServiceMain at /Users/fred/WebKit/Source/WebKit/Shared/API/Cocoa/WKMain.mm:36 #40 0x0000000102b0470c in main at /Users/fred/WebKit/Source/WebKit/Shared/EntryPointUtilities/Cocoa/AuxiliaryProcessMain.cpp:32 #41 0x000000018314fe80 in start ()

Created attachment 481799 [details] dumped render tree

(In reply to Frédéric Wang Nélar from comment #5) > I can reproduce a crash with > https://hachyderm.io/@mikeymikey/117106856897792159 but the backtrace seems > quite different: > > https://searchfox.org/wubkat/rev/b934faaa9c958fb3278550542b2eb3b127e363f2/ > Source/WebCore/page/LocalFrameViewLayoutContext.cpp#97 I forgot say that contrary to the initial report, the crash I mentioned can be reproduced directly with https://hachyderm.io/@mikeymikey/117106856897792159 ; no need to scroll down on the timeline https://hachyderm.io/@mikeymikey I added the full backtrace and dumped dirty tree. But the testcase is still big and would need some reduction.