I believe there may be a bug in Firefox Sync for Mac. We've had a few users report on the support forum that they need to sign into Firefox Sync each time they open Firefox. This issue started appearing when Firefox 70 was released and it appears to be Mac-exclusive.

Not having a Mac means that I can't test this bug or provide any insight on the issue. I just think that it seems very coincidental that multiple instances of the same problem have started popping up and only with users of Mac.

Here are a few of the threads that I have saved from users reporting the problem:

• I've just downloaded 64 bit Firefox on my Mac with the Catalina OS and now I have to sign into Firefox everytime I open it. Is this the new normal?
• Everytime I open firefox 70.0 it asks me to login into my firefox account, how can I get it to stay logged in??
• Everytime I open Firefox, none of my bookmarks, passwords, or history are saved. How do I change this?

Thanks for escalating this!

In at least one of these cases (this one) this seems to be a more general problem with Firefox creating an entirely new profile on every launch, and being signed out of Sync is just the most user-visible symptom. I'm going to see if I can find out who the appropriate person is to comment on whether this is a broader profile-related problem.

In at least one of these cases (this one) this seems to be a more general problem with Firefox creating an entirely new profile on every launch

The fine folks in #firefox on slack suggested that this can be caused by users executing Firefox directly from the downloaded .dmg file, rather than copying the app to their local disk; ref Bug 1314074 for related discussion.

We do sometimes see a bump in reports like this after an upgrade. I can't find a single good bug to point at, but something like bug 1295122 can be the case. It might be worth asking the users to (1) sign back in, (2) restart the browser, (3) open the "browser console" immediately after startup and copy any messages pasted there and (4) open about:sync-log and paste the contents of the most recent log file shown.

https://support.mozilla.org/en-US/questions/1274546

The priority flag is not set for this bug.
:markh, could you have a look please?

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I'm marking this a P3 on Mark's behalf - not because it isn't an important bug, but because we don't have any solid leads as to why this might be happening. I've tried to follow up in a few of the SUMO threads but haven't gotten any responses.

However, I do notice that at least one thread my question about "are you running directly from the disk image" was selected as the "chosen solution":

https://support.mozilla.org/en-US/questions/1274546

So I guess that's a signal that Bug 1314074 is the cause of this error in at least one case..?