Filed by: apavel [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer?job_id=334514690&repo=mozilla-central
Full log: https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/KlLlCh_ISiSE9lqF1AH8Mw/runs/0/artifacts/public/logs/live_backing.log

[task 2021-03-26T04:58:51.997Z] 04:58:51     INFO - TEST-START | devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js
[task 2021-03-26T04:58:52.272Z] 04:58:52     INFO - GECKO(3054) | console.error: "Tried to send a 'target-destroyed-form' event on an already destroyed actor 'watcher'"
[task 2021-03-26T04:58:52.373Z] 04:58:52     INFO - GECKO(3054) | ###!!! [Parent][RunMessage] Error: Channel closing: too late to send/recv, messages will be lost
[task 2021-03-26T04:58:52.374Z] 04:58:52     INFO - GECKO(3054) | ###!!! [Parent][RunMessage] Error: Channel closing: too late to send/recv, messages will be lost
[task 2021-03-26T04:58:52.660Z] 04:58:52     INFO - GECKO(3054) | console.error: "Tried to send a 'target-destroyed-form' event on an already destroyed actor 'watcher'"
[task 2021-03-26T04:58:53.575Z] 04:58:53     INFO - GECKO(3054) | console.error: "Tried to send a 'getTarget' method reply on an already destroyed actor 'workerDescriptor'"
[task 2021-03-26T04:58:53.838Z] 04:58:53     INFO - GECKO(3054) | -----------------------------------------------------
[task 2021-03-26T04:58:53.838Z] 04:58:53     INFO - GECKO(3054) | Suppressions used:
[task 2021-03-26T04:58:53.838Z] 04:58:53     INFO - GECKO(3054) |   count      bytes template
[task 2021-03-26T04:58:53.838Z] 04:58:53     INFO - GECKO(3054) |      14        448 nsComponentManagerImpl
[task 2021-03-26T04:58:53.838Z] 04:58:53     INFO - GECKO(3054) |       2        288 libfontconfig.so
[task 2021-03-26T04:58:53.838Z] 04:58:53     INFO - GECKO(3054) | -----------------------------------------------------
[task 2021-03-26T04:58:53.974Z] 04:58:53     INFO - GECKO(3054) | -----------------------------------------------------
[task 2021-03-26T04:58:53.975Z] 04:58:53     INFO - GECKO(3054) | Suppressions used:
[task 2021-03-26T04:58:53.975Z] 04:58:53     INFO - GECKO(3054) |   count      bytes template
[task 2021-03-26T04:58:53.976Z] 04:58:53     INFO - GECKO(3054) |      14        448 nsComponentManagerImpl
[task 2021-03-26T04:58:53.976Z] 04:58:53     INFO - GECKO(3054) |       2        288 libfontconfig.so
[task 2021-03-26T04:58:53.976Z] 04:58:53     INFO - GECKO(3054) | -----------------------------------------------------
[task 2021-03-26T05:00:22.010Z] 05:00:22     INFO - TEST-INFO | started process screentopng
[task 2021-03-26T05:00:22.253Z] 05:00:22     INFO - TEST-INFO | screentopng: exit 0
[task 2021-03-26T05:00:22.254Z] 05:00:22     INFO - Buffered messages logged at 04:58:52
[task 2021-03-26T05:00:22.254Z] 05:00:22     INFO - Entering test bound 
[task 2021-03-26T05:00:22.254Z] 05:00:22     INFO - Test TargetCommand against local tab descriptor (via getTab({ tab }))
[task 2021-03-26T05:00:22.255Z] 05:00:22     INFO - Adding a new tab with URL: https://example.org/document-builder.sjs?html=org
[task 2021-03-26T05:00:22.256Z] 05:00:22     INFO - Tab added and finished loading
[task 2021-03-26T05:00:22.257Z] 05:00:22     INFO - Console message: [JavaScript Error: "The character encoding of the HTML document was not declared. The document will render with garbled text in some browser configurations if the document contains characters from outside the US-ASCII range. The character encoding of the page must be declared in the document or in the transfer protocol." {file: "https://example.org/document-builder.sjs?html=org" line: 0}]
[task 2021-03-26T05:00:22.257Z] 05:00:22     INFO - TEST-PASS | devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js | Got a unique target - 
[task 2021-03-26T05:00:22.257Z] 05:00:22     INFO - TEST-PASS | devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js | The first is the top level one - 
[task 2021-03-26T05:00:22.259Z] 05:00:22     INFO - TEST-PASS | devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js | the tab target is of frame type - 
[task 2021-03-26T05:00:22.259Z] 05:00:22     INFO - TEST-PASS | devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js | This is flagged as top level - 
[task 2021-03-26T05:00:22.260Z] 05:00:22     INFO - Test TargetCommand against remote tab descriptor (via getTab({ outerWindowID }))
[task 2021-03-26T05:00:22.261Z] 05:00:22     INFO - Adding a new tab with URL: https://example.org/document-builder.sjs?html=org
[task 2021-03-26T05:00:22.262Z] 05:00:22     INFO - Tab added and finished loading
[task 2021-03-26T05:00:22.263Z] 05:00:22     INFO - Console message: [JavaScript Error: "The character encoding of the HTML document was not declared. The document will render with garbled text in some browser configurations if the document contains characters from outside the US-ASCII range. The character encoding of the page must be declared in the document or in the transfer protocol." {file: "https://example.org/document-builder.sjs?html=org" line: 0}]
[task 2021-03-26T05:00:22.263Z] 05:00:22     INFO - TEST-PASS | devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js | Got a unique target - 
[task 2021-03-26T05:00:22.263Z] 05:00:22     INFO - TEST-PASS | devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js | TargetCommand top target is the same as the first target - 
[task 2021-03-26T05:00:22.264Z] 05:00:22     INFO - TEST-PASS | devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js | the tab target is of frame type - 
[task 2021-03-26T05:00:22.264Z] 05:00:22     INFO - TEST-PASS | devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js | This is flagged as top level - 
[task 2021-03-26T05:00:22.265Z] 05:00:22     INFO - TEST-PASS | devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js | Without fission, the top target stays the same - 
[task 2021-03-26T05:00:22.266Z] 05:00:22     INFO - Test TargetCommand against parent process descriptor
[task 2021-03-26T05:00:22.267Z] 05:00:22     INFO - Console message: [JavaScript Error: "The character encoding of the HTML document was not declared. The document will render with garbled text in some browser configurations if the document contains characters from outside the US-ASCII range. The character encoding of the page must be declared in the document or in the transfer protocol." {file: "https://example.com/document-builder.sjs?html=org" line: 0}]
[task 2021-03-26T05:00:22.268Z] 05:00:22     INFO - Buffered messages finished
[task 2021-03-26T05:00:22.269Z] 05:00:22     INFO - TEST-UNEXPECTED-FAIL | devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js | Test timed out - 
[task 2021-03-26T05:00:22.271Z] 05:00:22     INFO - Not taking screenshot here: see the one that was previously logged
[task 2021-03-26T05:00:22.271Z] 05:00:22     INFO - TEST-UNEXPECTED-FAIL | devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js | The main process DevToolsServer has no pending connection when the test ends - 
[task 2021-03-26T05:00:22.272Z] 05:00:22     INFO - Stack trace:
[task 2021-03-26T05:00:22.272Z] 05:00:22     INFO - chrome://mochikit/content/browser-test.js:test_ok:1331
[task 2021-03-26T05:00:22.272Z] 05:00:22     INFO - chrome://mochitests/content/browser/devtools/client/shared/test/shared-head.js:cleanup:319
[task 2021-03-26T05:00:22.273Z] 05:00:22     INFO - GECKO(3054) | console.error: "Error when attaching target:" (new Error("Connection closed, pending request to server0.conn16.workerDescriptor26, type getTarget failed\n\nRequest stack:\nrequest@resource://devtools/shared/protocol/Front.js:285:14\ngenerateRequestMethods/</frontProto[name]@resource://devtools/shared/protocol/Front/FrontClassWithSpec.js:46:19\ngetTarget/this._attach<@resource://devtools/client/fronts/descriptors/worker.js:92:44\nasync*getTarget@resource://devtools/client/fronts/descriptors/worker.js:105:7\nattach@resource://devtools/client/fronts/descriptors/worker.js:64:17\n_attachAndInitThread@resource://devtools/client/fronts/targets/target-mixin.js:477:20\nattachAndInitThread@resource://devtools/client/fronts/targets/target-mixin.js:456:40\n_onTargetAvailable@resource://devtools/shared/commands/target/target-command.js:166:25\n_processNewWorkerTarget@resource://devtools/shared/resources/legacy-target-watchers/legacy-workers-watcher.js:136:18\n_workerListChanged/promises<@resource://devtools/shared/resources/legacy-target-watchers/legacy-workers-watcher.js:112:12\n_workerListChanged@resource://devtools/shared/resources/legacy-target-watchers/legacy-workers-watcher.js:111:30\nasync*_onProcessAvailable@resource://devtools/shared/resources/legacy-target-watchers/legacy-workers-watcher.js:38:16\nlisten@resource://devtools/shared/resources/legacy-target-watchers/legacy-workers-watcher.js:153:18\nasync*startListening@resource://devtools/shared/commands/target/target-command.js:325:47\nasync*testParentProcess@chrome://mochitests/content/browser/devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js:34:20\nasync*@chrome://mochitests/content/browser/devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js:23:9\nAsync*Tester_execTest/<@chrome://mochikit/content/browser-test.js:1089:34\nTester_execTest@chrome://mochikit/content/browser-test.js:1129:11\nnextTest/<@chrome://mochikit/content/browser-test.js:949:14\nSimpleTest.waitForFocus/waitForFocusInner/focusedOrLoaded/<@chrome://mochikit/content/tests/SimpleTest/SimpleTest.js:1037:23\n", "resource://devtools/shared/protocol/Front.js", 99))
[task 2021-03-26T05:00:22.274Z] 05:00:22     INFO - GECKO(3054) | console.error: "Tried to call watchFronts for the 'serviceWorkerRegistration' type on an already destroyed front 'root'."
[task 2021-03-26T05:00:22.276Z] 05:00:22     INFO - Not taking screenshot here: see the one that was previously logged
[task 2021-03-26T05:00:22.276Z] 05:00:22     INFO - TEST-UNEXPECTED-FAIL | devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js | Uncaught exception received from previously timed out test - at resource://devtools/shared/protocol/Front/FrontClassWithSpec.js:28 - Error: Can not send request 'listServiceWorkerRegistrations' because front 'root' is already destroyed.
[task 2021-03-26T05:00:22.276Z] 05:00:22     INFO - Stack trace:
[task 2021-03-26T05:00:22.276Z] 05:00:22     INFO - generateRequestMethods/</frontProto[name]@resource://devtools/shared/protocol/Front/FrontClassWithSpec.js:28:15
[task 2021-03-26T05:00:22.277Z] 05:00:22     INFO - _updateRegistrations@resource://devtools/shared/resources/legacy-target-watchers/legacy-serviceworkers-watcher.js:209:30
[task 2021-03-26T05:00:22.278Z] 05:00:22     INFO - _onRegistrationListChanged@resource://devtools/shared/resources/legacy-target-watchers/legacy-serviceworkers-watcher.js:170:16
[task 2021-03-26T05:00:22.278Z] 05:00:22     INFO - listen@resource://devtools/shared/resources/legacy-target-watchers/legacy-serviceworkers-watcher.js:83:16
[task 2021-03-26T05:00:22.278Z] 05:00:22     INFO - startListening@resource://devtools/shared/commands/target/target-command.js:325:47
[task 2021-03-26T05:00:22.279Z] 05:00:22     INFO - async*testParentProcess@chrome://mochitests/content/browser/devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js:34:20
[task 2021-03-26T05:00:22.279Z] 05:00:22     INFO - async*@chrome://mochitests/content/browser/devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js:23:9
[task 2021-03-26T05:00:22.280Z] 05:00:22     INFO - Async*Tester_execTest/<@chrome://mochikit/content/browser-test.js:1089:34
[task 2021-03-26T05:00:22.281Z] 05:00:22     INFO - Tester_execTest@chrome://mochikit/content/browser-test.js:1129:11
[task 2021-03-26T05:00:22.281Z] 05:00:22     INFO - nextTest/<@chrome://mochikit/content/browser-test.js:949:14
[task 2021-03-26T05:00:22.282Z] 05:00:22     INFO - SimpleTest.waitForFocus/waitForFocusInner/focusedOrLoaded/<@chrome://mochikit/content/tests/SimpleTest/SimpleTest.js:1037:23
[task 2021-03-26T05:00:22.282Z] 05:00:22     INFO - GECKO(3054) | MEMORY STAT | vsize 20975151MB | residentFast 1318MB
[task 2021-03-26T05:00:22.283Z] 05:00:22     INFO - TEST-OK | devtools/shared/commands/target/tests/browser_target_list_various_descriptors.js | took 90152ms
[task 2021-03-26T05:00:22.283Z] 05:00:22     INFO - checking window state```

https://wiki.mozilla.org/Bug_Triage#Intermittent_Test_Failure_Cleanup
For more information, please visit auto_nag documentation.