Firefox just got upgraded to version 57. Unfortunately this version breaks compatibility with an add-on that I rely on. Until support for add-ons improves, I want to stick with a version that works.

It's too late to block the upgrade, now I need to downgrade. I have an APK of the old version, downloaded from apkmirror (though I would prefer an official source of I could find one). But how do I install it without losing my settings?

After some fumbling with methods that rejected downgrades, I found a way:

adb install -r -d org.mozilla.firefox_56.*.apk

This did downgrade, but then Firefox systematically crashed on startup.

I guess it's too late for me --- I uninstalled and reinstalled, leaving I had to reinstall my add-ons, bookmarks, saved passwords, etc. But I'm sure I'm not the only one who got bien or is about to get bitten by the Quantum update. So how can one downgrade Firefox without losing settings?

  • Close to impossible I'm afraid, unless you happen to also have a backup of your profile folder from before the update. FF57 changed many things in the structures of that, too. Some things could be saved by exporting them before the downgrade (I'm sure about bookmarks, as they can be exported to HTML) and then import them again later. Another option would be, instead of downgrading FF, additionally installing Waterfox: at least on desktop, it can import from FF. And it's compatible to FF55 currently. Not sure how that works on Android, though (copying a profile).
    – Izzy
    Nov 20, 2017 at 0:22
  • @Izzy I hadn't heard of Waterfox, thanks. Does it even work of Android? I forgot to mention that my phone is a Fairphone 2, so not ARMv8, and it's running Android 5.1 (the latest version on FP2 :(). Nov 20, 2017 at 0:26
  • Waterfox just released an Android version a month ago. Haven't tried it myself. There's a Waterfox on Playstore, but I'm not sure if that's the very one (last version from 9/2015 – also the size of 1.5M hardly matches Waterfox' ~33M, website doesn't match either). Until it arrives somewhere (Playstore, F-Droid) you can find it on their homepage.
    – Izzy
    Nov 20, 2017 at 7:07


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