Bug: Intermittent browser/components/doh/test/browser/browser_NextDNSMigration.js | Uncaught exception - [Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIObserverService.removeObserver]"  nsresult: "0x80004005 (NS_ERROR_FAILUR
Status: RESOLVED
Priority: P5
Resolution: DUPLICATE
Created: 2021-08-21 00:42:31+00:00
Resolved: 2022-07-26 00:14:48+00:00

**Filed by:** abutkovits [at] mozilla.com
**Parsed log:** https://treeherder.mozilla.org/logviewer?job_id=349094533&repo=autoland
**Full log:** https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/dJEP_lIvSt6PO3PgtZWXYg/runs/0/artifacts/public/logs/live_backing.log

---
```
[task 2021-08-20T23:40:36.527Z] 23:40:36     INFO - TEST-START | browser/components/doh/test/browser/browser_NextDNSMigration.js
[task 2021-08-20T23:40:36.536Z] 23:40:36     INFO - TEST-INFO | started process screenshot
[task 2021-08-20T23:40:36.607Z] 23:40:36     INFO - TEST-INFO | screenshot: exit 0
[task 2021-08-20T23:40:36.612Z] 23:40:36     INFO - Buffered messages logged at 23:40:36
[task 2021-08-20T23:40:36.613Z] 23:40:36     INFO - Entering test bound setup
[task 2021-08-20T23:40:36.613Z] 23:40:36     INFO - Buffered messages finished
[task 2021-08-20T23:40:36.615Z] 23:40:36     INFO - TEST-UNEXPECTED-FAIL | browser/components/doh/test/browser/browser_NextDNSMigration.js | Uncaught exception - [Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIObserverService.removeObserver]"  nsresult: "0x80004005 (NS_ERROR_FAILURE)"  location: "JS frame :: resource:///modules/DoHController.jsm :: _uninit :: line 196"  data: no]
[task 2021-08-20T23:40:36.615Z] 23:40:36     INFO - Stack trace:
[task 2021-08-20T23:40:36.616Z] 23:40:36     INFO - _uninit@resource:///modules/DoHController.jsm:196:18
[task 2021-08-20T23:40:36.616Z] 23:40:36     INFO - setup@chrome://mochitests/content/browser/browser/components/doh/test/browser/head.js:71:23
[task 2021-08-20T23:40:36.616Z] 23:40:36     INFO - Tester_execTest/<@chrome://mochikit/content/browser-test.js:1091:34
[task 2021-08-20T23:40:36.616Z] 23:40:36     INFO - Tester_execTest@chrome://mochikit/content/browser-test.js:1131:11
[task 2021-08-20T23:40:36.616Z] 23:40:36     INFO - nextTest/<@chrome://mochikit/content/browser-test.js:939:14
[task 2021-08-20T23:40:36.616Z] 23:40:36     INFO - SimpleTest.waitForFocus/<@chrome://mochikit/content/tests/SimpleTest/SimpleTest.js:1041:13
[task 2021-08-20T23:40:36.616Z] 23:40:36     INFO - Leaving test bound setup
[task 2021-08-20T23:40:36.617Z] 23:40:36     INFO - Entering test bound testNextDNSMigration
[task 2021-08-20T23:40:36.617Z] 23:40:36     INFO - Not taking screenshot here: see the one that was previously logged
[task 2021-08-20T23:40:36.618Z] 23:40:36     INFO - TEST-UNEXPECTED-FAIL | browser/components/doh/test/browser/browser_NextDNSMigration.js | Uncaught exception - [Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIObserverService.removeObserver]"  nsresult: "0x80004005 (NS_ERROR_FAILURE)"  location: "JS frame :: resource:///modules/DoHController.jsm :: _uninit :: line 196"  data: no]
[task 2021-08-20T23:40:36.618Z] 23:40:36     INFO - Stack trace:
[task 2021-08-20T23:40:36.618Z] 23:40:36     INFO - _uninit@resource:///modules/DoHController.jsm:196:18
[task 2021-08-20T23:40:36.618Z] 23:40:36     INFO - restartDoHController@chrome://mochitests/content/browser/browser/components/doh/test/browser/head.js:295:23
[task 2021-08-20T23:40:36.618Z] 23:40:36     INFO - testNextDNSMigration@chrome://mochitests/content/browser/browser/components/doh/test/browser/browser_NextDNSMigration.js:36:9
[task 2021-08-20T23:40:36.618Z] 23:40:36     INFO - Tester_execTest/<@chrome://mochikit/content/browser-test.js:1091:34
[task 2021-08-20T23:40:36.619Z] 23:40:36     INFO - Leaving test bound testNextDNSMigration
[task 2021-08-20T23:40:36.619Z] 23:40:36     INFO - GECKO(8280) | MEMORY STAT | vsize 2104115MB | vsizeMaxContiguous 65925576MB | residentFast 203MB | heapAllocated 80MB
[task 2021-08-20T23:40:36.620Z] 23:40:36     INFO - TEST-OK | browser/components/doh/test/browser/browser_NextDNSMigration.js | took 25ms
[task 2021-08-20T23:40:36.620Z] 23:40:36     INFO - checking window state
```