Created attachment 365776 [details] Crash Log The following layout tests are crashing on Mac http/wpt/mediarecorder/MediaRecorder-AV-audio-video-dataavailable.html imported/w3c/web-platform-tests/mediacapture-record/MediaRecorder-constructor.html Probable cause: These two tests have been crashing on the bots for months. Have been unable to reproduce locally. Recently these have been causing EWS to cause other patches to fail. Found a way to reproduce the crashes locally when running the tests with the test runners from the bots and it will reproduce the same crash the bots are seeing. Reproduced with : run-webkit-tests imported/w3c/web-platform-tests/css/cssom/css-style-attr-decl-block.html imported/w3c/web-platform-tests/mediacapture-record/MediaRecorder-constructor.html --child-processes 1 --no-retry run-webkit-tests http/tests/security/xssAuditor/script-tag-safe4.html http/wpt/mediarecorder/MediaRecorder-AV-audio-video-dataavailable.html --child-processes 1 Flakiness Dashboard: https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=http%2Fwpt%2Fmediarecorder%2FMediaRecorder-AV-audio-video-dataavailable.html https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=imported%2Fw3c%2Fweb-platform-tests%2Fmediacapture-record%2FMediaRecorder-constructor.html Crash Logs attached : Thread 0 Crashed:: Dispatch queue: com.apple.main-thread 0 com.apple.WebCore 0x0000000107d7b4e3 WTFCrashWithInfo(int, char const*, char const*, int) + 19 1 com.apple.WebCore 0x0000000108153b20 initAVEncoderBitRateKey() + 128 2 com.apple.WebCore 0x000000010814db26 WebCore::MediaRecorderPrivateWriter::setAudioInput() + 38 3 com.apple.WebCore 0x000000010814da2e WebCore::MediaRecorderPrivateWriter::create(WebCore::MediaStreamTrackPrivate const*, WebCore::MediaStreamTrackPrivate const*) + 574
*** This bug has been marked as a duplicate of bug 193724 ***
<rdar://problem/49191228>
<rdar://problem/49191229>