If you’re like me, you’ve been using Firefox for awhile, and you love when a new version comes out. At the same time however, you’re dreading it because you know there’s a good chance some of your favorite plug-ins won’t work (at least not right away).
As an example, I use a Firefox extension “Signature” all the time for posting repetitive things like signatures, but also sometimes for complete responses to frequently asked questions. I might have 3 or 4 paragraphs of text saved that I could easily drop in with this plug-in.
Unfortunately, the signature plug-in isn’t compatible with version 3.0 of Firefox (as of this writing). Does this mean you just have to do without? Well if it did, there wouldn’t be much need to right this article now would there? 
New Life for Old Add-ons
Firefox add-ons are usually installed automatically by visiting the Firefox add-ons page and clicking on your add-on of choice. This action downloads an .XPI file and your Firefox browser does the rest.
Well we can do a little tweaking of the XPI file and change a few lines to make it work with Firefox 3.0. Here’s what we do (I’ll use “Signature” as an example:
Trying to download the extension, you’ll notice that the option is grayed out because Firefox knows the version is not coded for the latest version
However, if you scroll down a little, you’ll see an option to see all versions.
This allows you to see previous versions that you can then right-click on and choose to “save link as”. This enables us to save the .xpi file to our PC which we can then open and tweak.
The XPI file is in essence a compressed archive, much like a ZIP, RAR or CAB file. You can use most unzipping type programs to open the file. I chose to use WinRAR. I opened WinRAR, then opened the .XPI file I saved locally.
I had to specify to look for *.XPI in the file name box, otherwise it doesn’t show up (it’s looking for it’s default file types, i.e. .zip, .rar, etc).
Once you open the .xpi file, you’re looking for a file called install.rdf. This can be opened with any text editor, my text editor of choice is Scite (link opens new window).
Edit the install.rdf file, and you’ll see a min and max version number for Firefox. Change the default maxVersion value from its default to the version you currently have or something slightly higher. In this case I chose to increment the version to 3.1.0.
Close the file, add it back into the .xpi file (easiest way is to open the .xpi file using WinRAR, drag the install.rdf to your desktop, edit the file, save the file, then drag the newly modified file back into the WinRAR application overwriting the original install.rdf file.
Once you’ve gotten the install.rdf file back into the .xpi file, open the file with Firefox (File > Open File). When you do, you’ll be prompted to install the extension.
Install the extension, restart your browser and you should have a newly working signature extension ready to be put back to good use!
July 21st, 2008 at 1:45 pm
It seems to me that Mozilla themselves can’t do much about missing ad-ons seeing as how they’re made by a bunch of random developers all around the world. If I was a developer I’d probably have moved on to something else and wouldn’t care about updating an old free non0profit ad-on.
July 21st, 2008 at 1:45 pm
Better yet..
1. Go to about:config
2. Right-click anywhere and create a new boolean. Name it “extensions.checkCompatibility” and set it to false.
Ta-da!
You may have to create an account and log into addons.mozilla.com for it to work, I forget.
July 21st, 2008 at 3:01 pm
I’ve tried that before, and it works most of the time, although I’ve had it crash Firefox a few times, where it wouldn’t load at all.
So the method I listed above has worked like a champ so far.
July 21st, 2008 at 3:43 pm
Sweeet! Thanks!
July 21st, 2008 at 4:00 pm
gr8 post though
July 21st, 2008 at 8:00 pm
If you download the Nightly Tester Tools add-on, you can force compatibility with a simple click…
August 18th, 2008 at 10:15 am
You’re welcome!
August 25th, 2008 at 11:54 pm
[...] 2- Firefox 3 - Make Older Add-ons Work | Palaestra Training [...]
August 26th, 2008 at 3:11 am
[...] 11- Firefox 3 - Make Older Add-ons Work | Palaestra Training [...]
October 1st, 2008 at 4:05 pm
[...] awesome! Oh wait, half my add-ons don’t work now…Garbage. Here’s a simple way to make Firefox2 add-ons run on Firefox 3, even if they have compatibility problems. Basically, you just edit a text file, it’s really [...]
November 8th, 2008 at 10:59 am
I had so many crashes on the latest Firefox versions, that I deleted it and downloaded http://www.FLOCK.com, and then imported all my Firefox extensions. Guess what: they all work smoothly and no more crashes.
Flock is much easier on my laptop and a very, VERY cute browser …..
November 15th, 2008 at 6:43 pm
Would this work for themes as well? I would LOVE to be able to use the ‘Red Shift’ theme! The developer of the theme IS TAKING HIS SWEET TIME developing a 3.0.0 compatible version! If this workaround doesn’t work for themes, would you happen to know of any that would work? Thanks in advance!
November 18th, 2008 at 3:21 am
Works with me. Nice one. Now I can do the same with some add ons who don´t work either.
December 19th, 2008 at 8:37 pm
about:config
extensions.checkCompatibility
extensions.checkUpdateSecurity
should both be set to false and all will work even if really old.
December 28th, 2008 at 10:35 am
Firefox 2 is great.
Why change a good thing?
Firefox 3 sucks.
What a shame.
The end of a good era.
——————
Another point.
Way back in the mid 70’s I was doing pretty much everything we can do now with far far less memory and almost no processing power. Why? because the software of today is Total Trash.
December 28th, 2008 at 12:08 pm
Back in the 70’s everything was text-based green screen so there really wasn’t a need for processing power aside from number crunching mathematical equations. Computers really only do four things 1) accept input, 2) processing the input, 3) producing output, 4) storing the data. So what we have these days are just prettier wrappers on the process, making it easier to use, more user-friendly, etc. Graphics is the big killer, as they just keep increasing every year and the need for more powerful graphics cards escalates (pushed of course by the billion dollar gaming industry).
The reality of that though, is that if you’re not into gaming, then it’s really irrelevant as you have no need to keep up with the bleeding edge. Now operating systems, that’s a different story…. I would agree I can’t see the reasons why each version of Windows gets increasingly fatter, seemingly slower, and requires more processing power. Most of the fancy effects and features in Vista can be found in any linux distribution running desktop effects with 1/2 the hardware requirements (and they run beautifully), virtual desktops, etc.
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