The Primary Password is only used to unlock the logins stored in the Password Manager and is used locally (not part of Sync) and is profile specific. If you cancel the PP prompt, Firefox won't be able to connect to the Sync account, but otherwise Firefox will work normally. *https://support.mozilla.org/en-US/kb/using-primary-password-sync *https://support.mozilla.org/en-US/kb/reset-your-primary-password-if-youve-forgotten-it See also: *https://support.mozilla.org/en-US/kb/ive-lost-my-firefox-sync-account-information