As Firefox (32-bit) was getting unresponsive, presumably due to maxing out its process RAM, I've just installed an official 64-bit version of Firefox from this page because i'm a developer and according to this page it's

The only browser made just for developers, Firefox Developer Edition was created with your workflow in mind. Build, test, scale and more all from one place, for the first time ever.

That lacks the option to import from my old Firefox profile, though. I've imported my Chrome stuff, but still wonder whether there's an equally simple way to get my old Firefox profile cookies and passwords into this fresh install.

  • 1
    Why did you install the dev build? Just install the 64-bit release version.
    – DavidPostill
    Jul 25, 2016 at 19:02

1 Answer 1


The safest, easiest option is to stick to the stable releases which use your existing active profile by default. If you're more adventurous and wish to stay with the dev version, read on:

Unfortunately, importing old profile data involves manual file copying and reinstallation and reconfiguration of addons, according to this page. So to merge profiles from different browsers, one must start by manually copying the old Firefox profile data files from %APPDATA%\Mozilla\Firefox\Profiles\:

  • places.sqlite for Bookmarks, Downloads and Browsing History.
  • key3.db and logins.json for saved passwords.
  • sessionstore.js for tabs that were open when Firefox crashed.

...unless you store your private data in the Mozilla cloud via Firefox Sync.

...or simply risk your old profile with unstable dev features by sharing it: Share your Firefox profile with the dev version

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