Created attachment 378689 [details] crash log The following assertion failure is seen on macOS Debug WK1 bots intermittently with layout test imported/w3c/web-platform-tests/IndexedDB/idbfactory-open-request-error.html ASSERTION FAILED: m_transactionMap.contains(transaction.info().identifier()) ./Modules/indexeddb/server/UniqueIDBDatabaseConnection.cpp(70) : void WebCore::IDBServer::UniqueIDBDatabaseConnection::abortTransactionWithoutCallback(WebCore::IDBServer::UniqueIDBDatabaseTransaction &) 1 0x109d1d4a9 WTFCrash 2 0x11c9569db WTFCrashWithInfo(int, char const*, char const*, int) 3 0x11e50bcc2 WebCore::IDBServer::UniqueIDBDatabaseConnection::abortTransactionWithoutCallback(WebCore::IDBServer::UniqueIDBDatabaseTransaction&) 4 0x11e519af8 WebCore::IDBServer::UniqueIDBDatabaseTransaction::abortWithoutCallback() 5 0x11e438213 WebCore::IDBServer::IDBServer::abortOpenAndUpgradeNeeded(unsigned long long, WebCore::IDBResourceIdentifier const&) 6 0x11e5d7d9f WebCore::InProcessIDBServer::abortOpenAndUpgradeNeeded(unsigned long long, WebCore::IDBResourceIdentifier const&)::$_45::operator()() const 7 0x11e5d7ca9 WTF::Detail::CallableWrapper<WebCore::InProcessIDBServer::abortOpenAndUpgradeNeeded(unsigned long long, WebCore::IDBResourceIdentifier const&)::$_45, void>::call() 8 0x109d49fba WTF::Function<void ()>::operator()() const 9 0x109dbb023 WTF::RunLoop::performWork() 10 0x109dbc4be WTF::RunLoop::performWork(void*) 11 0x7fff40a10683 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ 12 0x7fff40a10629 __CFRunLoopDoSource0 13 0x7fff409f3feb __CFRunLoopDoSources0 14 0x7fff409f35b5 __CFRunLoopRun 15 0x7fff409f2ebe CFRunLoopRunSpecific 16 0x10877162b runTest(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) 17 0x10877082a runTestingServerLoop() 18 0x10876ff53 dumpRenderTree(int, char const**) 19 0x10877203d DumpRenderTreeMain(int, char const**) 20 0x1087fa342 main 21 0x7fff6c9493d5 start https://build.webkit.org/results/Apple%20Mojave%20Debug%20WK1%20(Tests)/r249817%20(5586)/results.html http://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=imported%2Fw3c%2Fweb-platform-tests%2FIndexedDB%2Fidbfactory-open-request-error.html
<rdar://problem/55323564>
Lots of changes have been made since this radar was filed. The test have not crashed for a few months now (since r253738). r253740 or later changes may have fixed this.