I have a new version of Firefox (46).
I need to install Firefox 44 to find a bug, that appears in a web app I am writing, but only in version 44 and older.
How do I do that? I don't want to have any conflicts, I don't want the older version to overwrite the current settings, etc.
Best Answer
You have three options.
You can check the link for details: Using portable firefox and fixing flash
Download the older version of firefox from the archive: Mozilla.org_ftp_site
Unzip to a path.
Next open terminal and use the following command to add a new firefox user.
firefox --no-remote -P
Create a new user, take note of the user-name.
Next, create a launcher for the 'firefox' you just unzip. Go inside the unzipped folder , there you will find a firefox file (probably binary) which launches the program. When creating the launcher, update the command as:
/path/to/unzipped/firefox --no-remote -P "<user-name>"
Creating launcher in Ubuntu
And now, when you will use this launcher then older firefox (which you want to use for testing) will open. Important - check the build version to verify.
In the url bar ->
about:
(Your newer version of firefox will not be affected, and it has
firefox --no-remote -P "default"
as command.)