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

Status: RESOLVED INACTIVE

(Core :: DOM: Security, defect)

Description

[Paul (FxUX)]

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.

Comment 5

[Daniel Veditz [:dveditz]]

Paul won't be able to look into it this week but will investigate after that. There's currently not enough information here to progress, so if we don't get more to go on in the next couple of weeks we'll have to close the bug

Comment 6

[Paul (FxUX)]

Although I caught the original instance of this happening on screen recording, I haven't noticed a repeat of this since the few times it happened before my original report.

Closing for now, and I'll raise another ticket if it happens again.

Comment 7

[Dão Gottwald [:dao]]

Paul told me this has happened again.

Comment 8

[Paul (FxUX)]

It has happened again where my container tabs closed unprompted while the app wasn't focused. After it happened, I noticed the setting for "Enable Container Tabs" was turned off. Is there a keyboard shortcut for it that I might have accidentally hit, which caused the setting to turn off (and so the tabs to disappear)?

I've found a secondary bug while testing this: I had some container tabs opened, and I tried to disable the 'Enable Container Tabs" setting.

It prompted me: “Close All Container Tabs? [Keep enabled] [ Close 1 container tab]”

I selected 'Keep enabled' and it closed my container tab and disabled the feature. I would expect "Keep enabled" to dismiss the option without doing anything.

Comment 9

[Daniel Veditz [:dveditz]]

It has happened again [...] After it happened, I noticed the setting for "Enable Container Tabs" was turned off. Is there a keyboard shortcut for it that I might have accidentally hit[?]

There should not be a keyboard shortcut for that! But it's kind of good news in the sense that the symptoms sounded exactly like containers got turned off, and you've confirmed that it was, in fact, turned off. We're no closer to figuring out how or why, but at least we can focus on mechanisms around that and don't have to wonder if something else closed pinned tabs and they just happened to be container tabs.

But just to be sure, please confirm that your tab settings normally looks like the top variant, and not the bottom variant of the screenshots I'm going to attach.

Second question: in the past when this happened did you notice that setting was turned off and manually re-enable it to start using container tabs, or did tabs just magically work again? From the initial description it sounds like restarting Firefox was a magic fix without having to do anything, but I want to triple check that before heading down blind alleys. Another mystery! So far I've got

1. how is this getting disabled?
2. how is this getting re-enabled?

I've found a secondary bug while testing this:

I can easily reproduce that so I'll assume that's unrelated for now. I'll see if there's a bug on file already and file a new one if there isn't.

One possible answer for mystery #2 might be a corrupted settings file. If you make other settings changes—say changing Tracking Protection from Standard to Strict or vice versa—and then restart Firefox, is the new setting honored or forgotten?

Comment 10

[Daniel Veditz [:dveditz]]

Attachment: Two ways "Enable container tabs" might look (dark mode)

Comment 11

[Paul (FxUX)]

It hasn't happened again since, so I'll close the ticket (again)