We've got a few bugs on file for intermittent test failures where on further inspection we see they are all on MacOS on a single machine. The ones I can find right now are:

• Bug 1568385 - t-mojave-r7-458
• Bug 1569389 - t-mojave-r7-458
• Bug 1529562 - t-yosemite-r7-320

Possibly there is some hardware fault on these machines. The failures are crashes that look like memory corruption and don't seem to be related to anything we've changed.

At first look these are both working fine after upgrading to MacOS 10.14(mojave):
https://tools.taskcluster.net/provisioners/releng-hardware/worker-types/gecko-t-osx-1014/workers/mdc1/t-mojave-r7-458
https://tools.taskcluster.net/provisioners/releng-hardware/worker-types/gecko-t-osx-1014/workers/mdc1/t-mojave-r7-320
both show many completed tasks and not repeated failures or exception/crashes.

I'll look at these more and confirm this before closing.

(In reply to Dave House [:dhouse] from comment #1)
Thanks for looking into this. I wouldn't expect these to fail all the time though, the concern is that they might have some bad RAM (or maybe some other hardware issue) that is causing intermittent problems. Is it possible to check the RAM on these machines?

Hasn't happened for a couple of months but all the failures in bug 1568385 were on a single machine.

There have been no failures since 9th September so I'm closing this.