(In reply to Andrew Sutherland [:asuth] (he/him) from comment #13)
Thanks for your assistance in digging into this deeper, Ryan. (Aside: I'm going to include various menu path you're probably already aware of and which I include for the benefit of anyone else who is able to reproduce.)
To rule out edge-cases, I first want to check: Do you use any settings in about:preferences#privacy (via the hamburger menu, "Preferences", then clicking on the "Privacy & Security" tab) that cause Firefox to clear data at shutdown? Specifically, have you either checked "Delete cookies and site data when Nightly is closed" under "Cookies and Site Data" or have you changed "Nightly will...Remember history" under "History" to something else?
I usually have the privacy set to strict, but I can still reproduce this with it set to the standard setting too.
Clear Offline Website Data is enabled on shut down. That's the only thing set there.
Assuming you have the defaults set there, then the question would be are there any incriminating looking error messages in the "Browser Console" when you start up Firefox? (The Browser Console is accessible from the hamburger menu under "Web Developer".) The errors would start with "Quota" that I would expect to happen. Then the other question is whether the devtools for either tab show anything interesting that mentions service workers. (They are accessible via hamburger menu, "Web Developer", "Toggle Tools".)
There is nothing of that sort listed in the logs at all. I have set the logs to persist to see if I missed anything of relevance. If there is, I cannot find it. I will include a copy of the log here for you to have a look, you might have a better idea as to what you're looking for.
Assuming there's nothing obvious there, what would be ideal is if we can use some other site that uses a ServiceWorker to test whether the problem is only happening at startup, or if it's also happening the first time you go to load a ServiceWorker even later in the browsing session. For example, https://whatwg.org/ uses a ServiceWorker. The general test idea here would be:
- Before shutting down the browser, go to https://whatwg.org/ and make sure the page loads and that a ServiceWorker has been installed.
- (Firefox gets shutdown.)
- Next time you start the browser, observe whether twitter/gmail are broken.
- Browse to https://whatwg.org/ via opening a new tab and typing, autocompleting, or pasting the URL. See if the page ends up blank with an empty URL bar similar to twitter/gmail. Knowing whether it loads okay or not would be very informative.
Fascinating. I have done this, exactly as you outlined and it does indeed reproduce the issue every time.
In the meantime we can try and add additional logging that would show up in the browser or devtool consoles that explain what's going on.
Thanks. If there is anything else you'd like me to try, please let me know. Happy to help pin this one down.