Manually Update Add-ons to Work

Update: Thanks to Ken Saunders for the suggestion to use 7-Zip instead of WinRAR. Using 7-Zip greatly simplifies this process.


I downloaded and installed Firefox 3.7a6pe today (more on this in another post). Everything was going fairly well until I started to move my extensions over from Firefox 3.6 profile. I was going to start with Nightly Tester Tools, but found out it is only compatible up to Firefox 3.7a5. Simple enough, I’ll just apply the Overriding Add-ons Compatibility Check Tweak I wrote earlier this year. That doesn’t seem to work with Firefox 3.7 or it may be related to the ‘problems with the new add-ons manager’ in Firefox 3.7 that people were mentioning in the Firefox Builds forum.

Last year I helped a family member get a theme they had been using to work with Firefox 3.5 and earlier this year with 3.6. This involves hacking the add-on (works with extension or theme) and modifying one line in the install.rdf file to make the add-on compatible with the newer version of Firefox.

WARNING! Forcing an add-on to work can cause unwanted behaviours including browser crash upon start-up. Familiarize yourself on how to use Firefox Safe-Mode.

Before you start you will need a file compression/archiving utility that supports .JAR files. 7-Zip works very well. Also I suggest using Notepad++ as it is a much better file editor than the traditional Notepad/Wordpad (DO NOT use a Word Processor such as MS Word). To associate Notepad++ as the editor for 7-Zip, in 7-Zip go to Tools >> Options.. > Editor and locate where Notepad++ is installed. Once you have these two applications installed and setup then you are ready to start:

  • Download the add-on. When on the addons.mozilla.org page right-click on the Add to Firefox button and choose Save Link As…
  • Locate the saved file. Right-click and from the context menu select 7-Zip >> Open Archive
  • Locate the install.rdf file within the 7-Zip interface right-click and select Edit this will open the default editor connected to 7-Zip.
  • Edit the install.rdf file. In your editor activate the find function (CTRL+F) and in the find box enter maxVersion (note: some add-ons may use the same install.rdf file for multiple applications be sure to make sure your editing the Firefox version).
  • To the right of this ‘tag’ you are going to see a number. This reflects the latest version of Firefox this add-on supports. You will want to change this to the next highest version of Firefox:
    • Using Firefox 3.5 change this number to 3.6
    • Using Firefox 3.6 change this number to 3.7
    • Using Firefox 3.7 change this number to 4.1
    • Using Firefox 4.0 change this number to 4.1
  • Save the file. Once you return to 7-Zip it should prompt you the file has been modified. Click OK to update the archive.
  • Drag the add-on file from the Explorer window into Firefox to install as normal