Make Older Firefox Extensions Compatible With Easy Hack

Ever wanted to run older extensions with your new Firefox release just to find the author hasn't created an updat3e yet. Well there are two easy ways to force compatibility of older extensions with some of the newer versions of the popular browser.
The first and easiest way is to use the Nightly Tester Tools Add-on. This extension is a quick easy way to run those add-ons and extensions you use with either new or nightly builds of Firefox, Thunderbird, Sunbird and Toolkit Seamonkey (Suiterunner).


The following is a brief list of the extension’s features, for the full set of features please take a look at the features list.

• Extension compatibility fixing
• Titlebar customisation
• Build ID retrieval
• Screenshots
• Breakpad information
• Restoring tabs from previous session
• Leak log analysis

Another easy way is to simply hack the existing code in the old add-on itself. This might sound a bit more complicated however it's a fairly simple process that only requires a user to change a few things.

To perform the hack for yourself, you'll want to start by downloading and saving the Firefox extension from .XPI to .ZIP. Once you've done that you can use your favorite ZIP program, I recommend 7Zip, and unzip it. From there you need to look for the install.rdf file open that file with “Notepad” so that you can change the number for the “maxVersion”.

The exact code looks like this
<em:maxVersion>some number</em:maxVersion>

Once you've changed the "maxVersion" to whichever build you are working on now zip up the contents again, rename the file from .ZIP back to .XPI, and then you can simply drag the file into the Firefox add-ons window to install it.


It should be noted that forcing an incompatible extension to install is risky. There are many cases where Firefox will stop working completely or behave incorrectly because an incompatible extension is being forced to work where the author never intended.