Rated 5 out of 5 stars

If you want to backup&restore your passwords in firefox 57, until the addon is compatible, just go to this folder:

C:\Users\YOURPROFILENAME\AppData\Roaming\Mozilla\Firefox\Profiles\
or paste this link in the folder explorer:
%APPDATA%\Mozilla\Firefox\Profiles\

Open the "xxxxxxxx.default" folder and backup these two files: "key3.db" and "logins.json".

Now you can restore your passwords, just place these two files in the new "profile folder" created after installing firefox 57.


more info: https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data