Migration of what? https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles https://support.mozilla.org/en-US/products/firefox/download-and-install/copy-info-to-another-browser https://support.mozilla.org/en-US/products/firefox/download-and-install https://support.mozilla.org/en-US/kb/export-login-data-firefox https://support.mozilla.org/en-US/questions/1232689 https://support.mozilla.org/en-US/questions/1323193

You can copy certain files with Firefox closed to the current profile folder to transfer/recover/backup your personal data. Note that best is to avoid copying a full profile folder. *https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data <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 (decryption key and 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)