How can I downgrade Firefox?

Solution 1:

There is no built-in rollback or downgrade function within Firefox. In fact, on their support page for the subject, they strongly insist that you do not roll back.

I rolled back a longstanding, many times upgraded, Firefox 57 to the specific version and bit depth below. I did not manually uninstall Firefox, but was prepared for things to go sideways. YMMV.

If you know better and don't want to heed their warnings, then do these steps:

1. Download an older version of Firefox here. If you are trying to back down from 57, you'll want to grab 56.0.2, (Windows US English version 32 bit exe) here. You can look at all of their 56.0.2 releases here.
2. Wait until the download finishes.
3. Find your profile folder. You can find where that is here. Also, this Mozilla Support article covers steps 3, 4, and 5 of this answer.
4. Close Firefox.
5. Back up your profile folder. You can simply copy the folder somewhere else, just in case stuff goes sideways.
6. Find the executable you downloaded in step 1.
7. Run it.
8. Go through the installer, and when its complete, launch Firefox.
9. My previous session, extensions, and settings were all as they were before the upgrade/downgrade. I was pleasantly surprised.

If your install is broken, try the usual steps to fix installation problems:

1. Completely uninstall Firefox via Programs and Features
2. Reboot
3. Run a cleanup utility like CCleaner.
4. Manually remove the leftovers and profile folder if you have to.
5. Install from the 56.0.2 executable you downloaded.
6. Verify it works with a new profile.
7. Restore your backed up profile (Mozilla Support)

See also: gHacks, MozillaZine.

Solution 2:

I didn't roll back my 16.10 installation of Firefox 57, but installed Firefox-ESR alongside it.

https://launchpad.net/~mozillateam/+archive/ubuntu/ppa

all my extensions seem to work fine

better yet.. https://www.mozilla.org/en-US/firefox/organizations/all/

Solution 3:

This answer is based on my answer on AskUbuntu - it suggests and describes howto install Firefox ESR 52.5 on Ubuntu and Mint.

I think it is better to downgrade to Firefox ESR 52 (this branch is planned to be supported until 2018-06-26 and will get security updates).

You have two options here:

• Get Firefox ESR 52.5.0 from Jonathon F's PPA. See my answer on a similar topic. You can install the package on 14.04 LTS (Trusty Tahr) and 16.04 LTS (Xenial Xerus) from this repository with the following commands:

  sudo add-apt-repository ppa:jonathonf/firefox-esr
  sudo apt-get update
  sudo apt-get install firefox-esr
  

Or

• Get Firefox ESR 52.5.0 from Mozilla Team's PPA (the first versions were published here at 2017-10-11 as the result of discussion on the ubuntu-desktop maillist). You can install the package on 14.04 LTS (Trusty Tahr), 16.04 LTS (Xenial Xerus), 17.04 (Zesty Zapus), 17.10 (Artful Aardvark), and 18.04 LTS (Bionic Beaver) from this repository with the following commands:

  sudo add-apt-repository ppa:mozillateam/ppa
  sudo apt-get update
  sudo apt-get install firefox-esr
  

For your information:

• The feature request for the official ESR package is located in Launchpad bug 1676164 and on the ubuntu-desktop maillist. At November I wrote a fresh message to this mail list with a link to the current question. I asked similar question on new community.ubuntu.com too.
• The current status of porting LEGACY extensions to WebExtension are located in Google Spreadsheet. The percentage of WebExtensions is not too high.

Debian already have official firefox-esr package.