When viewing the test results in https://ews-build.s3-us-west-2.amazonaws.com/iOS-15-Simulator-WK2-Tests-EWS/456643-12406/results.html, following links to view crashlogs for imported/w3c/web-platform-tests/html/cross-origin-embedder-policy/report-only-require-corp.https.html as well as the com.apple.WebKit.GPU.Development take you to a page with the following: <Error> <Code>NoSuchKey</Code> <Message>The specified key does not exist.</Message> https://ews-build.s3-us-west-2.amazonaws.com/iOS-15-Simulator-WK2-Tests-EWS/456643-12406/imported/w3c/web-platform-tests/html/cross-origin-embedder-policy/report-only-require-corp.https-crash-log.txt
Here is the buildbot link: https://ews-build.webkit.org/#/builders/68/builds/12406
Another example here with two tests: https://ews-build.s3-us-west-2.amazonaws.com/iOS-15-Simulator-WK2-Tests-EWS/456639-12403/results.html https://ews-build.webkit.org/#/builders/68/builds/12403
We can download the zip file which was uploaded from https://ews-build.s3-us-west-2.amazonaws.com/iOS-15-Simulator-WK2-Tests-EWS/456643-12406.zip It also doesn't seems to have the corresponding crash log file. So the bug doesn't seems to be on buildbot/ews side, but rather in webkitpy.
I see this quite frequently.
<rdar://problem/91632054>