Sign into your Mozilla account. I assume you're trying to sync your phone with another device. That is what sync is for, syncing data between 2 or more devices and '''not a back-up service.''' Sync info... '''FYI... Firefox Sync IS NOT A DATA BACKUP SERVICE''' https://support.mozilla.org/en-US/kb/how-do-i-set-sync-my-computer https://support.mozilla.org/en-US/kb/how-do-i-choose-what-information-sync-firefox https://www.mozilla.org/en-US/firefox/features/sync/ https://hacks.mozilla.org/2018/11/firefox-sync-privacy/ '''Sync is not a backup tool but it is a good sync/transfer/move tool''' https://support.mozilla.org/en-US/forums/contributors/707681