location used for the main profile that keeps your personal data (Root Directory on about:profiles).

Firefox uses two folders in a hidden location for the Firefox profile folder. One location for personal data like bookmarks and logins and another location for temporary files like the disk cache. location used for the main profile that keeps your personal data (Root Directory on about:profiles). *~/Library/Application Support/Firefox/Profiles/&lt;profile&gt; Secondary location used for the disk cache and other temporary files (Local Directory on about:profiles). *~/Library/Caches/Firefox/Profiles/&lt;profile&gt; In Mac OS X v10.7 and later, the "~/Library" folder in the Home directory is a hidden folder. *https://www.macworld.co.uk/how-to/mac-software/hidden-files-mac-3520878/ ---- You can copy certain files with Firefox closed to thecurrent profile folder to recover 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)