Hi birdwatcher42,

Thanks for the detailed report — this definitely sounds frustrating, especially since you've already tried the key troubleshooting steps.

Since you're on a MacBook Pro with an M3 Max chip running macOS Sequoia, and you've already attempted:

• Reinstalling Firefox

• Rebooting

• Refreshing Firefox

• Monitoring with Little Snitch

...here are a few other steps you could try that might help isolate or resolve the issue:

  *  Launch Firefox with a new profile (without affecting your current one): 

Open Terminal and run: /Applications/Firefox.app/Contents/MacOS/firefox-bin -P Create a new profile and see if Firefox launches and browses normally. If it does, the issue may be profile-specific.

• Run Firefox with logging enabled: To check if it crashes early, run: /Applications/Firefox.app/Contents/MacOS/firefox-bin --console This might show more context before the crash.

• Test with Rosetta emulation (for Apple Silicon): Right-click Firefox > Get Info > check “Open using Rosetta” and see if behavior changes. This can sometimes help work around binary compatibility issues.

• Use Firefox ESR temporarily: If the issue keeps recurring on standard releases, try Firefox ESR which is more conservative with updates and may offer better stability on your setup.

Also, since the issue seems to resolve inconsistently after a day, it's possible there’s an interaction with a background service, system cache, or something network-related that resets or updates periodically.

Let me know if you'd like help capturing logs or filing a Bugzilla report. Happy to help dig deeper.

— Nathan

Nathan: Thank you so much for the extensive suggestions!

Some interesting results to report.

1. First my binary was /Applications/Firefox.app/Contents/MacOS/firefox (without the "-bin" at the end); I assume that does not make any difference...?

2. Using "...firefox -P" I created a new profile and everything worked! I started copying over a few personalizations (bookmarks, cookies, etc.) to the new profile but then when I launched it was back to my same "failure mode". Long story short—the personalizations were a red herring. A new profile works fine the first time I launch; if I just close and restart Firefox it is back to my failure mode!

3. From either "...firefox -P" or "...firefox --console" I get one console message: "UNSUPPORTED (log once): POSSIBLE ISSUE: unit 1 GLD_TEXTURE_INDEX_2D is unloadable and bound to sampler type (Float) - using zero texture because texture unloadable". Sounds like that is a warning rather than an error. Also that warning appears at the Choose User Profile dialog, before even creating a new profile, so pretty sure that is innocuous.

4. Rosetta emulation made no difference.

5. Have not explored Firefox ESR yet...

Hoping you might have some ideas around the peculiar behavior in (2).