Filed by: csabou [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer?job_id=330873860&repo=mozilla-central
Full log: https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/TleE_aTbSV-kqIxt5dQEow/runs/0/artifacts/public/logs/live_backing.log

[task 2021-02-23T09:25:41.054Z] 09:25:41     INFO - TEST-PASS | devtools/client/framework/test/browser_target_parents.js | All the targets returned by concurrent calls to getTarget are the same - 
[task 2021-02-23T09:25:41.055Z] 09:25:41     INFO - Leaving test bound 
[task 2021-02-23T09:25:41.055Z] 09:25:41     INFO - Entering test bound 
[task 2021-02-23T09:25:41.055Z] 09:25:41     INFO - Buffered messages finished
[task 2021-02-23T09:25:41.056Z] 09:25:41     INFO - TEST-UNEXPECTED-FAIL | devtools/client/framework/test/browser_target_parents.js | Uncaught exception - at chrome://mochitests/content/browser/devtools/client/framework/test/browser_target_parents.js:65 - TypeError: can't access property "descriptorFront", addonFront is null
[task 2021-02-23T09:25:41.056Z] 09:25:41     INFO - Stack trace:
[task 2021-02-23T09:25:41.056Z] 09:25:41     INFO - @chrome://mochitests/content/browser/devtools/client/framework/test/browser_target_parents.js:65:1
[task 2021-02-23T09:25:41.056Z] 09:25:41     INFO - Async*@chrome://mochitests/content/browser/devtools/client/framework/test/browser_target_parents.js:62:8
[task 2021-02-23T09:25:41.056Z] 09:25:41     INFO - Async*Tester_execTest/<@chrome://mochikit/content/browser-test.js:1089:34
[task 2021-02-23T09:25:41.056Z] 09:25:41     INFO - async*Tester_execTest@chrome://mochikit/content/browser-test.js:1129:11
[task 2021-02-23T09:25:41.056Z] 09:25:41     INFO - nextTest/<@chrome://mochikit/content/browser-test.js:949:14
[task 2021-02-23T09:25:41.056Z] 09:25:41     INFO - SimpleTest.waitForFocus/waitForFocusInner/focusedOrLoaded/<@chrome://mochikit/content/tests/SimpleTest/SimpleTest.js:1037:23
[task 2021-02-23T09:25:41.061Z] 09:25:41     INFO - Leaving test bound 
[task 2021-02-23T09:25:41.061Z] 09:25:41     INFO - Entering test bound 
[task 2021-02-23T09:25:41.061Z] 09:25:41     INFO - GECKO(2220) | [Parent 2220, Main Thread] WARNING: NS_ENSURE_TRUE(rootFrame) failed: file /builds/worker/checkouts/gecko/dom/base/nsGlobalWindowOuter.cpp:4254
[task 2021-02-23T09:25:41.061Z] 09:25:41     INFO - TEST-PASS | devtools/client/framework/test/browser_target_parents.js```

This might be related to the patches landed in Bug 1685474: https://bugzilla.mozilla.org/show_bug.cgi?id=1685474#c13
Alexandre, please have a look over these kind of failures. Thank you.

Set release status flags based on info from the regressing bug 1685474

I reverted patches from Bug 1685474 (using hg diff -r bb6cddd372c2c95b04ce2930c8f7362822472d01 -r 7d8728cb6a1d --reverse to generate the patch and then applying it), and I was still able to trigger the test failure.
Cosmin, are there any other suspect for this regression?

There are ~6 failures/day. The first failure is this one and none of the 13 retriggers and backfills reproduced the issue but the issues hit another 3 times in the next 3 hours which suggested the failure is a regression from one of those check-ins near the first failure.

So retriggers point to Bug 1690573. Before that there are Android only changes (Bug 1684923) and two pushes each with 40 green runs.
Failure log: https://treeherder.mozilla.org/logviewer?job_id=331837453&repo=autoland
Mike, could you have a look over these failures? Thank you.

Better acknowledge that connectToFrame may resolve null in case of
destroyed addon while connectToFrame was processing.

https://hg.mozilla.org/mozilla-central/rev/3e0113209ceb
https://hg.mozilla.org/mozilla-central/rev/57eab193fdc5