How to downgrade Firefox Version on ubuntu

In  this tutorial I will show you how to downgrade your firefox version in this case from firefox 47.0 to 45.

First run this command:


apt-cache show firefox | grep Version

then you will see a list of available Firefox versions:

• Version: 47.0+build3-0ubuntu0.16.04.1
• Version: 45.0.2+build1-0ubuntu1

Now, run the next command to install the desired firefox version

sudo apt-get install firefox=28.0+build2-0ubuntu2

Finally, you have to avoid upgrading to the newer version.


sudo apt-mark hold firefox

And that's all.



If for any reason you do not see the version that you want, that means that version is very old.
To install a very old version of Firefox, you need to do the following:



1. First you must uninstall your current Firefox version.

  

$ sudo apt-get purge firefox

2. Then run the following command to download firefox 47.0 source code, which comes as .tar file.

 
$ wget http://ftp.mozilla.org/pub/firefox/releases/47.0/firefox-47.0.linux-i686.sdk.tar.bz2

3. Extract the package.

 $ tar -xjf firefox-47.0.linux-i686.sdk.tar.bz2

4. Move firefox to /opt directory.

 $ sudo mv firefox /opt/

5. Create symlink in order to set the new Firefox as default.

$ sudo mv /usr/bin/firefox /usr/bin/firefox_old

$ sudo mv /usr/bin/firefox /usr/bin/firefox_old

6.  Avoid upgrading to the newer version.

$ sudo apt-mark hold firefox

Note: This is the original source [here]