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How do I get my 32-bit FF session loaded into 64-bit FF?

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  • Last reply by cor-el

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I have just installed 64-bit FF. I can see that tabs have synched, but not previous 32-bit session. How can I migrate that session?

I have just installed 64-bit FF. I can see that tabs have synched, but not previous 32-bit session. How can I migrate that session?

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You can copy sessionstore.jsonlz4 from the 32-bit profile to the 64-bit profile, but if both versions are the same and are from the Mozilla server and not from the Microsoft store, then there is nothing against using the 32-bit profile with the 64-bit version provided that you no longer intent to use the 32-bit version and have uninstalled it. You can remove compatibility.ini in a profile to make this possible and use the Profile Manager to select this profile.

You can use the button on the "Help -> More Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page (Root directory).


You can copy certain files with Firefox closed to the current profile folder to transfer or recover personal data. Note that best is to avoid copying a full profile folder.


  • 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;32+) and key4.db (decryption key;58+) for Passwords saved in the Password Manager
    key3.db support ended in 73+; to use key3.db in 58-72, make sure to remove key4.db
  • cert9.db (58+) for (intermediate) 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)