Yes, Firefox 3.6.28:

• https://ftp.mozilla.org/pub/mozilla.org/firefox/releases/latest-3.6/

• http://www.mozilla.org/en-US/firefox/3.6.28/system-requirements/

Note that Firefox 3.6.28 is outdated and has a lot of unpatched security vulnerabilities and some websites may not work properly with this version.

What don't you like in current Firefox versions?

Maybe there is a workaround possible via settings in about:config or otherwise via extensions.

Firefox 3.6.x was dropped from support a LONG time ago, and is vulnerable to many dozens of Security holes, and is quite slow and unstable when compared to recent versions of Firefox. You should update to Firefox 20.0.1 immediately.

Common questions after upgrading from Firefox 3.6

3.6.28 is the last official release of that series. It is only a year old so it still works fine on 99.99% of websites. You can run multiple instances of Firefox including different versions at the same time by running the command: firefox.exe -P -no-remote

This will pop up a menu allowing you to create new user profiles - make a different one for each version (google: firefox multiple versions for detailed instructions). That way you can keep using 3.6.28 until you find a version that you prefer or only use the newer version for specific web pages if you are having issues with your old browser.

• http://kb.mozillazine.org/Profile_Manager#Creating_a_new_profile
• http://kb.mozillazine.org/Shortcut_to_a_specific_profile
• http://kb.mozillazine.org/Using_multiple_profiles_-_Firefox
• http://kb.mozillazine.org/Bypassing_the_Profile_Manager

Create a desktop shortcut with -P "profile" appended to the target to launch Firefox with each profile.
Then you can set in the profile manager which profile to use by default if you click a link in an external program.

Use the -no-remote command line switch to open another Firefox instance with its own profile and to run different Firefox instances simultaneously, but do not use -no-remote with the default browser and the default profile.

• http://kb.mozillazine.org/Opening_a_new_instance_of_Firefox_with_another_profile

Firefox 3.6 was made officially EOL on April 24th 2012 after about 27 1/2 months. There are no more security updates for the old Firefox 3.6 as the 3.6.28 was the last.

It originally came close to being EOL earlier back about Firefox 3.6.19 in 2011 but it then became the reluctant older supported version after Firefox 4.0 was released and then continued to get security updates until 3.6.28.

The reason I reverted back to version 3.6 is because with the latest version of firefox my most important addons no longer work

Can you tell us which add-ons you are referring to?

A lot of add-ons have a new version under a different name that works with Firefox 4 and later versions.