1896127 - (Pinned) container tabs randomly close / vanish any time, even when using a different app

Status: NEW

(Core :: DOM: Security, defect)

Description

[Paul]

Summary: Pinned container tabs randomly close / vanish any time, even when using a different app. After happening, the 'Open in new container tab' option is missing from the context menu until I quit and reopen Fx

Component: Tabs

Version / OS: Release 125.0.3 and Nightly 127.0a1, Mac OS Sonoma 14.4.1. It has happened a few times in the last few days.

Description: I don't know whether it's just pinned tabs, or just container tabs, or a combination of both. I will investigate more to try to narrow it down. Slack me for a screen recording of it happening, where 5 pinned container tabs just suddenly disappear, bringing a different tab to the front.

Steps to reproduce: There's no way that I know to reproduce it, as it happens even when Firefox is in the background. For example it happened when I was on a Zoom call, and it happened a few seconds after waking my Mac today.

Actual: my most important tabs close without me doing anything
Expected: them not doing that :)

Comment 1

[Dão Gottwald [:dao]]

When this happens again, could you please check the state of privacy.userContext.enabled in about:config? The "Open in new container tab" option disappearing seems to indicate it's a problem with container tabs specifically, and there's code that would remove all container tabs when the privacy.userContext.enabled pref changes to false: https://searchfox.org/mozilla-central/source/toolkit/components/contextualidentity/ContextualIdentityService.sys.mjs#157-161

Comment 2

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

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

For more information, please visit BugBot documentation.

Comment 3

[Daniel Veditz [:dveditz]]

Description: I don't know whether it's just pinned tabs, or just container tabs, or a combination of both. I will investigate more to try to narrow it down

First: do you have an add-on installed that enabled container tabs (e.g. the Multi-Account Containers add-on)? Or did you go to settings and check the "Enable Container Tabs" box without installing any other add-on?

If it's enabled because of an add-on, is it possible something is disabling that add-on? I agree w/Dao that it sounds like the feature is getting switched off somehow. I can't imagine how if you've manually set just the pref (those shouldn't change willy-nilly), but if you've got an add-on there are some behind-the-scenes checks that happen and maybe a bug happening during one of those is the culprit.

If this is affecting pinned container tabs and not other container tabs then that theory goes right out the window (leaving me with no ideas).

Comment 4

[Daniel Veditz [:dveditz]]

The "Enable Container Tabs" checkbox in about:preferences is directly connected to the privacy.userContext.enabled pref Dao mentioned. If you've installed a container-using add-on that will also enable that pref and it will disable your ability to edit the "Enable Container Tabs" checkbox until you've removed that add-on.