Are you using Sync as this is a possible reason to ask for the Primary Password when you start Firefox ?

Using Sync is a possible reason to ask for the Primary Password at startup. This is because the credentials to login to the Sync account are stored in the Password Manager and you need to enter the Primary Password to unlock the passwords and connect/login to the Sync account.

• https://support.mozilla.org/en-US/kb/using-primary-password-sync

Thanks. I did not realize that sync was activated on my PC. Disconnecting solved my issue.

For whatever reason, Firefox seems to have turned sync on by itself. I need to turn it off, but there is no option to do that, only to log in. To make it worse, I have different profiles (a wall between my financial accounts and my general browsing). It is not clear how to prevent the different profiles from syncing with each other, an obvious no-no. That is because it looks like the only way to do that would be to get different emails to use with different profiles.

I have been using using Firefox for privacy reasons. This new policy of opting out of syncing but only after creating an account is counter to that. I am deeply disappointed.