2033596 - Perma [tier 2] browser/extensions/newtab/test/browser/browser_customize_menu_content.js | test_render_customizeMenu - Uncaught exception in test - TypeError: can't access property "MutationObserver", subject.documentGlobal is undefined

Status: RESOLVED FIXED

(Firefox :: New Tab Page, defect, P5)

Description

[Treeherder Bug Filer]

Filed by: agoloman [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer?job_id=561281061&repo=autoland&task=KI2WY0cJTwGLpBL0sHXPug.0
Full log: https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/KI2WY0cJTwGLpBL0sHXPug/runs/0/artifacts/public/logs/live_backing.log

---

[task 2026-04-20T20:23:18.974+00:00] 20:23:18     INFO - TEST-PASS | browser/extensions/newtab/test/browser/browser_customize_menu_content.js | test_render_customizeMenu - Shortcuts section is not rendered - true == true
[task 2026-04-20T20:23:18.979+00:00] 20:23:18     INFO - Buffered messages finished
[task 2026-04-20T20:23:18.979+00:00] 20:23:18     INFO - TEST-UNEXPECTED-FAIL | browser/extensions/newtab/test/browser/browser_customize_menu_content.js | test_render_customizeMenu - Uncaught exception in test - TypeError: can't access property "MutationObserver", subject.documentGlobal is undefined
[task 2026-04-20T20:23:18.980+00:00] 20:23:18     INFO - waitForMutationCondition/<@resource://testing-common/ContentTaskUtils.sys.mjs:203:17
[task 2026-04-20T20:23:18.980+00:00] 20:23:18     INFO - waitForMutationCondition@resource://testing-common/ContentTaskUtils.sys.mjs:202:12
[task 2026-04-20T20:23:18.980+00:00] 20:23:18     INFO - promiseSectionShown@chrome://mochitests/content/browser/browser/extensions/newtab/test/browser/browser_customize_menu_content.js:75:31
[task 2026-04-20T20:23:18.980+00:00] 20:23:18     INFO - test_render_customizeMenu@chrome://mochitests/content/browser/browser/extensions/newtab/test/browser/browser_customize_menu_content.js:116:50
[task 2026-04-20T20:23:18.980+00:00] 20:23:18     INFO - async*execute@resource://testing-common/SpecialPowersSandbox.sys.mjs:139:12
[task 2026-04-20T20:23:18.980+00:00] 20:23:18     INFO - _spawnTask@resource://testing-common/SpecialPowersChild.sys.mjs:1624:15
[task 2026-04-20T20:23:18.980+00:00] 20:23:18     INFO - receiveMessage@resource://testing-common/SpecialPowersChild.sys.mjs:256:21
[task 2026-04-20T20:23:18.980+00:00] 20:23:18     INFO - JSActor query*receiveMessage@resource://testing-common/SpecialPowersParent.sys.mjs:1415:14
[task 2026-04-20T20:23:18.980+00:00] 20:23:18     INFO - JSActor query*spawn@resource://testing-common/SpecialPowersChild.sys.mjs:1551:17
[task 2026-04-20T20:23:18.980+00:00] 20:23:18     INFO - testTask@chrome://mochitests/content/browser/browser/extensions/newtab/test/browser/head.js:222:47
[task 2026-04-20T20:23:18.980+00:00] 20:23:18     INFO - async*handleTask@chrome://mochikit/content/browser-test.js:1380:26
[task 2026-04-20T20:23:18.980+00:00] 20:23:18     INFO - _runTaskBasedTest@chrome://mochikit/content/browser-test.js:1470:18
[task 2026-04-20T20:23:18.980+00:00] 20:23:18     INFO - async*Tester_execTest@chrome://mochikit/content/browser-test.js:1621:14
[task 2026-04-20T20:23:18.980+00:00] 20:23:18     INFO - nextTest/<@chrome://mochikit/content/browser-test.js:1360:14
[task 2026-04-20T20:23:18.980+00:00] 20:23:18     INFO - SimpleTest.waitForFocus/<@chrome://mochikit/content/tests/SimpleTest/SimpleTest.js:1060:13
[task 2026-04-20T20:23:18.980+00:00] 20:23:18     INFO - Leaving test test_render_customizeMenu
[task 2026-04-20T20:23:18.981+00:00] 20:23:18     INFO - Entering test test_render_customizeMenuWeather
[task 2026-04-20T20:23:19.199+00:00] 20:23:19     INFO - GECKO(3694) | console.log: PrefsFeed: "Activation window evaluation skipped."
[task 2026-04-20T20:23:19.199+00:00] 20:23:19     INFO - GECKO(3694) | console.debug: PrefsFeed: "enabled:false, createdInstant:2026-04-20T20:21:06.899Z, variant: "
[task 2026-04-20T20:23:19.686+00:00] 20:23:19     INFO - TEST-PASS | browser/extensions/newtab/test/browser/browser_customize_menu_content.js | test_render_customizeMenuWeather - Weather pref is turned off - true == true

Comment 1

[Emilio Cobos Álvarez [:emilio]]

This seems expected given the trainhop nature of this test. Do you know how to deal with this Mike?

Comment 2

[Intermittent Failures Robot]

38 failures were associated with this bug yesterday.

Repository breakdown:

• autoland: 38

Table

	trainhop-beta	trainhop-rel
linux2404-x86_64/opt	6	4
macosx1015-x86_64/opt	7	11
windows11-x86_64/opt	5	5

For more details, see:

https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=2033596&startday=2026-04-20&endday=2026-04-20&tree=all

Comment 3

[Intermittent Failures Robot]

187 failures were associated with this bug yesterday.

Repository breakdown:

• autoland: 175
• mozilla-central: 12

Table

	trainhop-beta	trainhop-rel
linux2404-x86_64/opt	43	37
macosx1015-x86_64/opt	20	20
windows11-x86_64/opt	33	34

For more details, see:

https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=2033596&startday=2026-04-21&endday=2026-04-21&tree=all

Comment 4

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 2033242

Comment 5

[Mike Conley (:mconley) (:⚙️)]

(In reply to Emilio Cobos Álvarez [:emilio] from comment #1)

This seems expected given the trainhop nature of this test. Do you know how to deal with this Mike?

Hi! Yeah, we're going to need to shim the usage of documentGlobal so that it falls back to ownerGlobal if documentGlobal does not exist.

Something like the ones we removed for the old Search service getter here: https://bugzilla.mozilla.org/show_bug.cgi?id=2024674

Comment 6

[Mike Conley (:mconley) (:⚙️)]

Attachment: Bug 2033596 - Shim documentGlobal in ContentTaskUtils.waitForMutationCondition for newtab train-hop tests until 152 makes it to release. r?emilio!

Comment 7

[Intermittent Failures Robot]

147 failures were associated with this bug yesterday.

Repository breakdown:

• autoland: 136
• mozilla-central: 11

Table

	trainhop-beta	trainhop-rel
linux2404-x86_64/opt	40	36
macosx1015-x86_64/opt	20	18
windows11-x86_64/opt	15	18

For more details, see:

https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=2033596&startday=2026-04-22&endday=2026-04-22&tree=all

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/d39046542722
https://hg.mozilla.org/integration/autoland/rev/d8b0688bd99d
Shim documentGlobal in ContentTaskUtils.waitForMutationCondition for newtab train-hop tests until 152 makes it to release. r=emilio

Comment 9

[Intermittent Failures Robot]

61 failures were associated with this bug yesterday.

Repository breakdown:

• autoland: 59
• mozilla-central: 2

Table

	trainhop-beta	trainhop-rel
linux2404-x86_64/opt	11	9
macosx1015-x86_64/opt	8	10
windows11-x86_64/opt	16	7

For more details, see:

https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=2033596&startday=2026-04-23&endday=2026-04-23&tree=all

Comment 10

[amarc]

https://hg.mozilla.org/mozilla-central/rev/d8b0688bd99d

Comment 11

[Intermittent Failures Robot]

461 failures were associated with this bug in the last 7 days.
This is the #1 most frequent failure this week.

This failure happened more than 75 times this week! Resolving this bug is a very high priority.

Try to resolve this bug as soon as possible. If unresolved for 1 week, the affected test(s) may be disabled.

Repository breakdown:

• autoland: 436
• mozilla-central: 25

Table

	no_variant	trainhop-beta	trainhop-rel
linux2404-x86_64/opt		100	86
macosx1015-x86_64/opt	2	67	73
windows11-x86_64/opt		69	64

For more details, see:

https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=2033596&startday=2026-04-20&endday=2026-04-26&tree=all