Closed Bug 1750973 Opened 2 years ago Closed 2 years ago

[Fission] TikTok videos not opening from user profiles


(Core :: DOM: Navigation, defect)

Firefox 96



98 Branch
Tracking Status
relnote-firefox --- 97+
firefox-esr91 --- disabled
firefox96 --- wontfix
firefox97 + verified
firefox98 + verified


(Reporter: x9trw0wk3, Assigned: smaug)


(Blocks 1 open bug, Regression)


(Keywords: regression)


(1 file)

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:96.0) Gecko/20100101 Firefox/96.0

Steps to reproduce:

In about:config, "fission.autostart" had set itself to true
I assume I was opted into some experiment


  • Go to
  • Navigate to any user profile
  • Scroll down
  • Click a video
  • Close it with the x
  • Try to click any other scrolled-down video

Actual results:

The page scrolls back to the top. The video fails to open.

This also happens on a brand new profile created via about:profiles, when fission.autostart is set to true

If fission.autostart is disabled and the browser is restarted, the behavior goes back to normal.

Expected results:

The video should have opened, the page shouldn't change its scroll position.

I.e. the behavior when fission.autostart is disabled

The Bugbug bot thinks this bug should belong to the 'Core::DOM: Navigation' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.

Component: Untriaged → DOM: Navigation
Product: Firefox → Core

Fission is enabled by default on all desktop versions of Firefox now, so it isn't an experiment exactly.

Summary: "Fission" Experiment Enrollment Breaks TikTok → [Fission] TikTok videos not opening from user profiles
Blocks: fission
Keywords: regression

I can reproduce the issue. The videos sometimes work when I click on them, but mostly not.

Ever confirmed: true

In a debug build, I didn't see any error messages of note with Fission enabled that didn't show up with it disabled.

Another odd thing is that it looks like the user profile pages are only single process, so I'm not sure how the behavior is going to change with Fission.

[Tracking Requested - why for this release]: Seems like a fairly common functionality on TikTok is not working, and was broken by Fission. I'm not exactly sure what the next steps are here, though.

Given that it is a single process page, Nika suggested that this could be a SHIP regression.

Flags: needinfo?(peterv)
Flags: needinfo?(bugs)

Bisected with Fission preffed on:
INFO: Last good revision: c25899d7b631470b983650ee254177381a62eaad (2020-10-02)
INFO: First bad revision: 33139800aca52aac192973fe24c9b74df7c87e00 (2020-10-03)
INFO: Pushlog:

Looks like it was indeed SHIP. Not sure it's worth trying to bisect further back with that force-enabled.

Has Regression Range: --- → yes
Has STR: --- → yes
Regressed by: 1668357

Thanks for doing the bisection, Ryan.

Blocks: ship-regressions
No longer blocks: fission

It does use pushState, but that seems to be working correctly. Still debugging.

Assignee: nobody → peterv

I have a patch but still trying to figure out the testcase.

Assignee: peterv → bugs
Flags: needinfo?(bugs)
Flags: needinfo?(peterv)
Pushed by
don't replace the nsILayoutHistoryState object when doing same document history navigations, r=peterv
Closed: 2 years ago
Resolution: --- → FIXED
Target Milestone: --- → 98 Branch

This seems worth taking as a dot release ride-along given that the fix is reasonably simple, includes tests, and affects a large site. Please nominate for release approval if you agree with that assessment.

Flags: needinfo?(bugs)

Yeah, I agree, it might be safe enough. Debugging the issue was extremely tricky and finding a test perhaps even trickier, but the fix is obvious.

Comment on attachment 9262002 [details]
Bug 1750973, don't replace the nsILayoutHistoryState object when doing same document history navigations, r=peterv

Beta/Release Uplift Approval Request

  • User impact if declined: Broken behavior in a commonly in a major website
  • Is this code covered by automated tests?: Yes
  • Has the fix been verified in Nightly?: Yes
  • Needs manual test from QE?: Yes
  • If yes, steps to reproduce: See the initial comment in the bug
  • List of other uplifts needed: None
  • Risk to taking this patch: Medium
  • Why is the change risky/not risky? (and alternatives if risky): The risk comes from the fact that the patch is changing session history handling. And based
    the experience, those changes tend to be rather regression risky.
    But this seems to be rather edge case which Tiktok somehow manages to rely on.
  • String changes made/needed: NA
Flags: needinfo?(bugs)
Attachment #9262002 - Flags: approval-mozilla-release?
Flags: qe-verify+
QA Whiteboard: [qa-triaged]

I have reproduced the issue on Firefox 97.0 and I've verified the fix on Firefox Beta 98.0b4 (20220213185901)

Comment on attachment 9262002 [details]
Bug 1750973, don't replace the nsILayoutHistoryState object when doing same document history navigations, r=peterv

Approved for 97.0.1.

Attachment #9262002 - Flags: approval-mozilla-release? → approval-mozilla-release+

Added to the 97.0.1 release notes.

Fixed an issue where TikTok videos would fail to load when selected from a user's profile page

Verified the fix on Firefox 97.0.1 (20220216142741)

QA Whiteboard: [qa-triaged]
Flags: qe-verify+
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