1981076 - Pinned tabs disappear or are not restored after restart on Windows 11 with Firefox 141.

Status: UNCONFIRMED

(Firefox :: Session Restore, defect)

Description

[Merlin Erdogmus [:Leterel]]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:141.0) Gecko/20100101 Firefox/141.0

Steps to reproduce:

On two devices (laptop and PC),
both running Windows 11 24H2 and Firefox version 141.
Pinned about 10–20 tabs in Firefox.
Closed Firefox normally after fresh system boot.
Reopened Firefox shortly after boot.

Actual results:

On the laptop (HP ProBook 445 G11, Ryzen 7 7735U, 48 GB DDR5 RAM), all pinned tabs disappeared completely after restart.

On the PC (MSI Creation X570, AMD 5950X, 64 GB DDR4 RAM, Windows 11 24H2), after restart pinned tabs were gone and browser engine became “dead” for the pinned tabs, although new tabs worked perfectly fine.

The browser acted as if there were no pinned tabs ever pinned,
and session restore did not bring any pinned tabs back.

Expected results:

Pinned tabs should be restored reliably after closing and reopening Firefox.
Session restore should bring back pinned tabs or at least not lose them completely.

Additional Details:
Issue appeared twice, once on laptop, once on PC.
Both machines are relatively high-end and up to date.
Laptop RAM was upgraded to 2x32GB DDR5.
I suspect it might be related to reopening
Firefox too soon after Windows boot, but not sure.
I now use bookmarks as a workaround for pinned tabs due to instability.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Firefox::Tabbed Browser' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Stephen Thompson [:sthompson]]

Hi :Leterel,

Thanks for the report. That sounds very frustrating. We expect pinned tabs to be restored to any open windows when reopening Firefox. Do you use any add-ons that interact with tabs? Could you please check whether you have session restore automatically enabled (“Open previous windows and tabs” in about:preferences)?

Closed Firefox normally after fresh system boot.
Can you please describe how many windows you had and how you closed the windows/the Firefox program?

browser engine became “dead” for the pinned tabs
Could you please describe this more? This might help us diagnose what happened to the pinned tabs.

Please attach any recent session restore logs from your profile directory, which - if they exist - should be in a a sessionstore-logs directory in your profile directory (the location is linked in the about:support page). This could help us identify what was happening on Firefox startup.

Comment 3

[Merlin Erdogmus [:Leterel]]

Hello Stephen and Firefox team,

Thank you for your response.

To clarify your questions:

• Add-ons: Yes, I use several extensions that interact with tabs and browsing. The active ones are:

  • AdGuard AdBlocker
  • Consent-O-Matic (handles GDPR consent automatically)
  • Dark Reader (dark mode for websites)
  • LanguageTool (grammar/spell check)
  • OneTab (tab management and memory saving)
  • Return YouTube Dislike
  • SponsorBlock for YouTube
  • uBlock Origin
  • Video DownloadHelper

• Session Restore setting: I have confirmed that “Open previous windows and tabs” is enabled in about:preferences.

• How Firefox was closed: I usually close Firefox normally via the standard close button after system boot and a fresh start, typically with one window open containing about 10–20 pinned tabs and some normal tabs. I do not force quit or kill the process manually.

• Description of "dead" browser engine for pinned tabs on PC: After restart, the pinned tabs appeared visually gone or inaccessible — the browser behaved as if those tabs were never pinned or opened. New tabs worked fine and were responsive, but the pinned tabs did not restore and the session restore did not bring them back.

• Session restore logs: Unfortunately, after the incident, I completely uninstalled Firefox and removed the profile to perform a clean reinstall. So I no longer have session logs to attach.

• Additional GUI bug: On my laptop (resolution 1920x1200), when I have around 20 pinned tabs and the space for normal tabs is very narrow, the minimize, maximize, and close window buttons flicker rapidly (~30 Hz). This is very distracting and only seems to happen when the window is sized such that the pinned tabs take up almost all horizontal space on the left half of the screen. Avoiding resizing the Firefox window to about 50% width on the left side prevents this flicker.

I suspect some race condition or session restore edge case may be involved, especially if Firefox is started too soon after Windows boot, but I have not been able to confirm this conclusively.

Please let me know if you need further details or testing from my side.

Thank you for looking into this.

Best regards,
Merlin

Comment 4

[Merlin Erdogmus [:Leterel]]

It just happened again.
I’ll switch to Waterfox.
Might change something, might not.
Let’s see.

Comment 5

[BugBot [:suhaib / :marco/ :calixte]]

The severity field is not set for this bug.
:dwalker, could you have a look please?

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