2024814 - inconsistent behavior occurs when closing window with tab groups

Status: UNCONFIRMED

(Firefox :: Tabbed Browser: Tab Groups, defect, P3)

Description

[Jason]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:148.0) Gecko/20100101 Firefox/148.0

Steps to reproduce:

Open multiple windows with one or multiple tab groups in each window

While keeping at least one window opened:

• open/close tabs in one of the windows
• close the window with changed tab group

Actual results:

only closing a tab will be persistent when re-opening the tab group.
New tab opened to the group will not be stored

Expected results:

If only one window is opened, changes to tab group(s) in said window are preserved after close and reopen Firefox

Closing and opening tabs should always update tab group after window closed

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

[Niklas Baumgardner [:niklas]]

Thanks for filing this bug!
Does this only reproduce with new tabs? Those don't get saved to the session.
Could you provide a screen recording of this bug. That would be very helpful for us to reproduce!

Comment 3

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

Redirect a needinfo that is pending on an inactive user to the triage owner.
:kcochrane, since the bug has recent activity, could you have a look please?

For more information, please visit BugBot documentation.

Comment 4

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

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

For more information, please visit BugBot documentation.

Comment 5

[Stephen Thompson [:sthompson]]

Hi, Jason, can you please confirm whether you see this behavior when adding tabs that contain loaded pages? We intentionally do not save empty tabs (about:blank, about:newtab, etc.) in tab groups.

Comment 6

[Jason]

Attachment: 2026-04-22-140426.mp4

add screen record for reproducing the behavior

Comment 7

[Jason]

(In reply to Stephen Thompson [:sthompson] from comment #5)

Hi, Jason, can you please confirm whether you see this behavior when adding tabs that contain loaded pages? We intentionally do not save empty tabs (about:blank, about:newtab, etc.) in tab groups.

please see the added video, opened tabs are loaded google home pages

Comment 8

[Jason]

Attachment: 2026-04-22-140517.mp4

behavior when only one window is opened

Comment 9

[Stephen Thompson [:sthompson]]

Thanks for the additional info and screen recording! That's very helpful. I'll take a look at the code that auto-saves a tab group when a window closes and see if there's any difference with when the browser shuts down completely with the last window closing.