Title: Transfer of Firefox passwords (across different versions)
Tags: firefox;password-management
Question: I'm using Firefox 60.2.2, but I have to go down to an old version (52-56) to use some add-on that's not compatible anymore.
I created another user profile, since I had the impression using the same profile across versions could mess things around. However, I need to use my username/passwords in my old version.
I thought that transfering the key.db and logins.json would suffice, but that's not the case.
How can I transfer password from the upgraded version to an old version?
Comment: BTW, ensure that automatic updates are turned off for the old version.  Otherwise, you'll go through all the work to set it up, and Firefox will replace it with the current version.

Comment: To list them for future reference, use Nirsoft's PasswordFox: https://www.nirsoft.net/utils/passwordfox.html . Regrettably, Firefox can *import* passwords from other browsers but has no built-in *export* function. sigh


Here is another answer: For transferral of the profile, passwords, bookmarks, etc use firefox sync. You will need to create the account on the older version, then login to sync on the newer version.
Comment for this answer: Before syncing, select to sync just passwords.  Otherwise, it might create havoc with new and old style add-ons.

Here is another answer: I understand that you are another victim of the Firefox decision to drop the XUL
add-on format, now called "Legacy", in favor of WebExtensions,
which are very similar to Google Chrome extensions.
I suggest using a Firefox-fork that still supports the old format.
My favorite is
Pale Moon.
You could use the
Pale Moon profile backup tool
to transfer your Firefox profile to Pale Moon, and there wouldn't be any
conflict since the two profiles will be kept in separate folders.

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