Importing from old firefox

[Xirix]

I'm currently using Firefox 89, the portable version. I've got an old long unused version of firefox on my PC (version 28) that I'd like to migrate all the info from, bookmarks, history, saved passwords etc, is it possible to grab all that and insert it into my up to date version, whilst still keeping the bookmarks and history etc of my current version?

[jscher2000]

Probably you will need to use some intermediate versions to upgrade the old profile because the conversion code is not retained indefinitely.

You could get the old portable for Firefox 45 and see whether it can handle upgrading the Firefox 28 profile. Then try Firefox 52, 60, 68, and 78 before Firefox 89.

https://sourceforge.net/projects/portab ... ble%20Ed./