How to update add-on compatibility manually

Some Firefox add-ons that are hosted at Mozilla are not compatible with the latest version of Firefox. Not because they would not be working or display errors but simply because the author did not update the add-on to be compatibly with the latest version of Firefox. Each Firefox add-on has two variables called min version and max version.

Min version specifies the Firefox version that has to be at least installed to run the add-on while max version specifies the Firefox version that can not be exceeded if you want to run the add-on. As I said it sometimes happens that a project is dead and that the author is not updating his add-on anymore.

Firefox then won’t install the add-on because of compatibility issues. It simply checks min and max versions and if those do not match it will reject the installation. One could use the Nightly Tester tools to force compatibility but also edit the installation file on its own to make it work.

Download the add-on to your hard drive. It has the xpi extension. Unpack the file. I use IZArc for it but most unpackers should do the same. The contents of the add-on should be extracted to your hard drive including a file called install.rdf.

Open the install.rdf file in a editor and search for minVersion and maxVersion. Change the values to of both entries so that your version of Firefox is compatible with the add-on and save the new file. Now drop it into the archive once again and install the add-on again.

The installation should go through without problems.