1617292 - "Strict" tracking protection sometimes causes all content to fail to display on browser launch

Status: NEW

(Core :: Privacy: Anti-Tracking, defect, P3)

Description

[Daniel Watkins]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:73.0) Gecko/20100101 Firefox/73.0

Steps to reproduce:

Enabled Strict tracking protection and, after several weeks of using Firefox, launched Firefox one day and the bug occurred. I have not been able to reliably reproduce it, though once in the buggy state, it reproduces on every launch.

I've experienced this on (Ubuntu's version of) 72.x and 73.x, as well as back in August on what would probably have been 68.x (but I didn't make a note).

Actual results:

No tabs would display any content. I restored my tabs, so this included pins, regular sites, and extension dialogs. Further to that, Firefox menus also wouldn't display; either via right-click on tabs, or via the "hamburger" menu in the top-right. (I could still close tabs via Ctrl-W for non-pinned tabs, or via middle-click for pinned tabs.)

favicons were displayed correctly, and I confirmed that the pages were actually being fetched from the remote sites because I typed the address for a page I know redirects and the redirect happened (specifically, "!g foo" in my address bar caused DuckDuckGo to redirect me to Google).

Restarting the browser did not fix this. Closing all of my tabs and restarting the browser did not fix this. Closing all of my tabs and restarting the browser, however, did allow the Firefox menus to render (provided I didn't try to open any web pages before using them), which allowed me to switch "Enhanced Tracking Protection" from Strict to Standard, fixing the problem (on browser restart).

I also noticed that at least part of the problem appears to apply only per-window: if I opened a new window then menus would render in that window (until I opened a web page).

I have been able to re-enable Strict mode on the first launch after switching away from it, and the browser continues to function normally.

Expected results:

Firefox should have behaved as it always does, displaying site content.

Comment 1

[Daniel Watkins]

I originally reported this downstream in Ubuntu here: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1861913

Comment 2

[Daniel Bodea [:danibodea]]

I did not manage to reproduce your issue using the provided information.
Daniel, When this issue occurs, can you check the Browser Console for errors and put them here?
Furthermore, since I do not really know what could cause this issue or how to troubleshoot it, please also go to the "about:support" page, copy and paste the information displayed about your system. Hopefully, it will help.

Thank you for your contribution!

Comment 3

[Daniel Watkins]

Attachment: raw_data.json

I don't see any errors in the Browser Console, only a warning: "unreachable code after return statement" in "injected.js:7:2". I've copied the raw data and attached it here.

Comment 4

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

The bug has a release status flag that shows some version of Firefox is affected, thus it will be considered confirmed.