Its great to upgrade your Mozilla Firefox browser whenever there is an update as it provide you with more new features and security updates. Demerits of upgrading to latest version is all the Addons / Extensions or Plugins you were using may not run on this latest release.

Suppose, you have 10 essential addons installed on your Firefox browser then 4 out of them will not be compatible with new version and the following Murphys Law – The most important one which you use most will fall in this category!

So, shouldn’t you have upgraded to latest version? NO, there is a small trick and you can run addons which are built for older versions of Firefox.

1. Type about:config in address bar and click the button to promise to be careful.
2. Right Click and select New > Boolean and name it extensions.checkCompatibility. Set its value to False.
3. Create another Boolean with name extensions.checkUpdateSecurity and set its value to False.

While downloading Addon from Firefox site, it may disable the button to download. In this case- click on See all version and Download.

Please note that you have to spend only few days after doing this tweak and there will be an update available for the incompatible addon from the Author itself to make it run on newer versions.

Another way to do it is using Nightly Tester Tools Addon for Firefox which will work for Theme compatibility fixing too.