Filed by: michael [at] masterwayz.nl
Parsed log: https://treeherder.mozilla.org/logviewer.html#?job_id=316003341&repo=autoland
Full log: https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/Fp2obsrMT7Oev7Q79w7cwg/runs/0/artifacts/public/logs/live_backing.log

> [task 2020-09-17T22:24:38.142Z] 22:24:38     INFO - TEST-UNEXPECTED-FAIL | /webdriver/tests/element_send_keys/send_keys.py | test_no_browsing_context - AssertionError
[task 2020-09-17T22:24:38.142Z] 22:24:38     INFO - session = <Session 0aabaee8-7af0-49cb-b568-717ea7ce5990>, closed_frame = None
[task 2020-09-17T22:24:38.142Z] 22:24:38     INFO - 
[task 2020-09-17T22:24:38.142Z] 22:24:38     INFO -     def test_no_browsing_context(session, closed_frame):
[task 2020-09-17T22:24:38.142Z] 22:24:38     INFO -         element = Element("foo", session)
[task 2020-09-17T22:24:38.142Z] 22:24:38     INFO -     
[task 2020-09-17T22:24:38.142Z] 22:24:38     INFO -         response = element_send_keys(session, element, "foo")
[task 2020-09-17T22:24:38.142Z] 22:24:38     INFO - >       assert_error(response, "no such window")
[task 2020-09-17T22:24:38.142Z] 22:24:38     INFO - 
[task 2020-09-17T22:24:38.142Z] 22:24:38     INFO - closed_frame = None
[task 2020-09-17T22:24:38.142Z] 22:24:38     INFO - element    = <Element foo>
[task 2020-09-17T22:24:38.142Z] 22:24:38     INFO - response   = <Response status=404 error=<NoSuchElementException http_status=404>>
[task 2020-09-17T22:24:38.142Z] 22:24:38     INFO - session    = <Session 0aabaee8-7af0-49cb-b568-717ea7ce5990>
[task 2020-09-17T22:24:38.142Z] 22:24:38     INFO - 
[task 2020-09-17T22:24:38.142Z] 22:24:38     INFO - tests\web-platform\tests\webdriver\tests\element_send_keys\send_keys.py:48: 
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO - 
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO - response = <Response status=404 error=<NoSuchElementException http_status=404>>
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO - error_code = 'no such window'
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO - 
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO -     def assert_error(response, error_code):
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO -         """
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO -         Verify that the provided webdriver.Response instance described
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO -         a valid error response as defined by `dfn-send-an-error` and
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO -         the provided error code.
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO -     
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO -         :param response: ``webdriver.Response`` instance.
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO -         :param error_code: String value of the expected error code
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO -         """
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO -         assert response.status == errors[error_code]
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO -         assert "value" in response.body
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO - >       assert response.body["value"]["error"] == error_code
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO - E       AssertionError
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO - 
[task 2020-09-17T22:24:38.143Z] 22:24:38     INFO - error_code = 'no such window'
[task 2020-09-17T22:24:38.144Z] 22:24:38     INFO - response   = <Response status=404 error=<NoSuchElementException http_status=404>>
[task 2020-09-17T22:24:38.144Z] 22:24:38     INFO - 
[task 2020-09-17T22:24:38.144Z] 22:24:38     INFO - tests\web-platform\tests\webdriver\tests\support\asserts.py:54: AssertionError
[task 2020-09-17T22:24:38.144Z] 22:24:38     INFO - ......```

Here the real failure:

https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=316003341&repo=autoland&lineNumber=6439-6457

[task 2020-09-17T22:24:36.751Z] 22:24:36     INFO - PID 3888 | 1600381476745	Marionette	DEBUG	1 -> [0,500,"WebDriver:ElementClick",{"id":"a5be2836-3ee1-43d6-8806-21a49953d2c5"}]
[task 2020-09-17T22:24:36.974Z] 22:24:36     INFO - PID 3888 | 1600381476969	Marionette	TRACE	Canceled page load listener because no navigation has been detected
[task 2020-09-17T22:24:36.974Z] 22:24:36     INFO - PID 3888 | 1600381476970	Marionette	DEBUG	1 <- [1,500,null,{"value":null}]
[task 2020-09-17T22:24:36.974Z] 22:24:36     INFO - PID 3888 | 1600381476970	webdriver::server	DEBUG	<- 200 OK {"value":null}
[task 2020-09-17T22:24:36.974Z] 22:24:36     INFO - PID 3888 | 1600381476972	webdriver::server	DEBUG	-> POST /session/0aabaee8-7af0-49cb-b568-717ea7ce5990/element/foo/value {"text": "foo"}
[task 2020-09-17T22:24:36.979Z] 22:24:36     INFO - PID 3888 | 1600381476975	Marionette	DEBUG	1 -> [0,501,"WebDriver:ElementSendKeys",{"id":"foo","text":"foo","value":["f","o","o"]}]
[task 2020-09-17T22:24:37.000Z] 22:24:37     INFO - PID 3888 | [Child 5612, Main Thread] WARNING: NS_ENSURE_TRUE(info) failed: file /builds/worker/checkouts/gecko/extensions/permissions/PermissionDelegateHandler.cpp, line 348
[task 2020-09-17T22:24:37.000Z] 22:24:37     INFO - PID 3888 | [Child 5612, Main Thread] WARNING: NS_ENSURE_TRUE(wc) failed: file /builds/worker/checkouts/gecko/extensions/permissions/PermissionDelegateHandler.cpp, line 344
[task 2020-09-17T22:24:37.000Z] 22:24:37     INFO - PID 3888 | [Child 5612, Main Thread] W1600381476995	Marionette	TRACE	[41] Frame with id 2147483650 got removed
[task 2020-09-17T22:24:37.000Z] 22:24:37     INFO - PID 3888 | ARNING: NS_ENSURE_TRUE(wc) failed: file /builds/worker/checkouts/gecko/extensions/permissions/PermissionDelegateHandler.cpp, line 344
[task 2020-09-17T22:24:37.000Z] 22:24:37     INFO - PID 3888 | [Child 5612, Main Thread] WARNING: NS_ENSURE_TRUE(wc) failed: file /builds/worker/checkouts/gecko/extensions/permissions/PermissionDelegateHandler.cpp, line 344
[task 2020-09-17T22:24:37.001Z] 22:24:37     INFO - PID 3888 | [Child 9692, Main Thread] WARNING: '!inner', file /builds/worker/checkouts/gecko/dom/ipc/jsactor/JSWindowActorProtocol.cpp, line 172
[task 2020-09-17T22:24:37.001Z] 22:24:37     INFO - PID 3888 | [Child 9692, Main Thread] WARNING: '!inner', file /builds/worker/checkouts/gecko/dom/ipc/jsactor/JSWindowActorProtocol.cpp, line 172
[task 2020-09-17T22:24:37.001Z] 22:24:37     INFO - PID 3888 | [Child 9692, Main Thread] WARNING: '!inner', file /builds/worker/checkouts/gecko/dom/ipc/jsactor/JSWindowActorProtocol.cpp, line 172
[task 2020-09-17T22:24:37.001Z] 22:24:37     INFO - PID 3888 | [Child 9692, Main Thread] WARNING: '!inner', file /builds/worker/checkouts/gecko/dom/ipc/jsactor/JSWindowActorProtocol.cpp, line 172
[task 2020-09-17T22:24:37.020Z] 22:24:37     INFO - PID 3888 | [Child 9692, Main Thread] WARNING: NS_ENSURE_TRUE(info) failed: file /builds/worker/checkouts/gecko/extensions/permissions/PermissionDelegateHandler.cpp, line 348
[task 2020-09-17T22:24:37.020Z] 22:24:37     INFO - PID 3888 | 1600381477006	Marionette	DEBUG	1 <- [1,501,{"error":"no such element","message":"Web element reference not seen before: foo","stacktrace":"WebDriverError@chrome: ... ch/</req<@chrome://marionette/content/listener.js:114:29\ndispatch/<@chrome://marionette/content/listener.js:113:15\n"},null]

The click seems to have caused the frame to get removed but we still seem to have a reference to it.

No more failures since October 9th. Marking as WFM.

New failure:
https://treeherder.mozilla.org/logviewer?job_id=323111991&repo=autoland&lineNumber=7802