cpearce says: I can reproduce the "InvalidStateError: Promise still outstanding at MediaKeys shutdown" error with clearkey if I induce the to CDM crash while there's a MediaKeySession.update() promise waiting to be resolved. I have not been able to reproduce this any other way. You would see this behaviour if the CDM crashed before you'd called HTMLMediaElement.setMediaKeys(). You can test this theory by checking whether the session's "closed" promise was unexpectedly resolved (i.e. MediaKeySession.closed resolved without you calling MediaKeySession.close() on the session first). Note that if the CDM process crashes after you've called HTMLMediaElement.setMediaKeys(), you'll also get a decode error event fired at the video element, i.e. there's two ways a CDM crash is observable to you. Hopefully some of the CDM crashes we've fixed will help reduce this error.
This was mostly an OS X 10.6 issue, which we no longer support. The error count has gone down.
We think Amazon has fixed this problem on their side.