If you still have access to the old device then you should be okay since you can reset the password of the Sync account and do the initial Sync on the old device again. Another option is to use a removable USB drive to transfer your personal data directly. You can copy certain files with Firefox closed from the profile folder on the old device to the profile folder on the new device to transfer your personal data. Note that best is to avoid restoring a full profile folder and only restore important files that are safe to restore/transfer. *https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data *https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile <hr> *bookmarks and history: places.sqlite *favicons: favicons.sqlite *bookmark backups: compressed .jsonlz4 JSON backups in the bookmarkbackups folder *cookies.sqlite for the Cookies *formhistory.sqlite for saved autocomplete Form Data *logins.json (encrypted logins) and key4.db (encryption key/primary password) for logins saved in the Password Manager *cert9.db for certificates stored in the Certificate Manager *persdict.dat for words added to the spell checker dictionary *permissions.sqlite for Permissions and possibly content-prefs.sqlite for other website specific data (Site Preferences) *sessionstore.jsonlz4 for open tabs and pinned tabs (see also the sessionstore-backups folder)