I’ve just updated my stable version of Firefox 3.0.3 to the latest Firefox 3.1 beta 1. I know I am putting my web browsing experience at risk because Firefox 3.1 is still under testing and development. So far so good as I still haven’t experience a single crash yet. It is able to load and end the firefox.exe process much faster than the current version when I close it. Firefox 3.1 introduces a new tab switching preview which I didn’t like so I disabled it.

One biggest problem that we always encounter is 99% of add-ons installed in Firefox wouldn’t work after installing the latest Firefox beta. There will be a warning window telling you that the following add-ons are not compatible with this version of Firefox and have been disabled.

Even if you go to the Firefox add-on page thinking that perhaps you can reinstall the disabled plugin, you wont’ be able to do that as well because if the add-on developer hasn’t updated their extension to work with Firefox beta, you’ll be seeing a message that says “This add-on is for older versions of Firefox”.

Although I don’t use a lot of Firefox add-ons and I probably can live without them for a while but it’d still be nice IF I can continue using them in Firefox Betas. Since I’ve already taken the risk of using Firefox BETA, I might as well go ahead and forcefully make the add-ons to work with Firefox beta. Here’s how I enable Firefox incompatible add-ons to work in Firefox 3.1 beta.

Before we continue, I’d like to warn you that forcing an incompatible extension to install in Firefox 3.1 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.

Here is a Firefox plugin called Nightly Tester Tools which gives you the power to enable the disabled incompatible extensions. After installing Nightly Tester Tools, go to Tools > Add-Ons > right click on any disabled plugins because of incompatibility and select “Override Compatibility”. If you want to enable ALL disabled plugins, simple click the Override all compatibility button located at the bottom of the Add-ons window.

I’d advice you to force install the incompatible add-ons one by one so you’ll know which is the culprit when you experience hangs, crashes, memory leaks, data corruption or other problems.

If you don’t want to use the Nightly Tester Tools, Firefox has a hidden (not so hidden now) setting where you can disable the add-on compatibility checking. Just follow the few simple steps below:

1. Type about:config into Firefox’s address bar and click the “I’ll be careful, I promise!” button.
2. Right-click on the Firefox window. Select New > Boolean.
3. When asked to enter the preference name, type extensions.checkCompatibility and click OK.
4. Make sure false is selected/highlighted and click OK. The end result should look something like the image below.

5. Restart Firefox and all your previously disabled incompatible add-ons will be enabled.

IF you accidentally selected String or Integer instead of Boolean at step 2, it won’t be so easy to delete the string from Firefox’s about:config. You’ll have to go to your Firefox profile folder which is by default at C:\Documents and Settings\\Application Data\Mozilla\Firefox\Profiles\XXXXXXXX.default. The will be the current logged on username and the XXXXXXXX is a randomly generated code for every profile. In the folder you’ll find a file called prefs.js. Open prefs.js with notepad or your favorite text editor, look for the string or integer that you want to delete and remove the line.

Finally, if you want to install an add-on from Firefox’s page, but seeing the message “This add-on is for older versions of Firefox”, here is how to bypass that restriction. Let’s take CustomizeGoogle add-on as an example.
1. Go to the CustomizeGoogle add-on page.
2. View the source code of the page. In Firefox, you can either hit Ctrl+U or go to View > Page Source to view the source. In Internet Explorer, click View from menu bar, and select Source. As for Opera, either hit Ctrl+U or go to View > Source.
3. Find for the text xpi at the source page. You can hit Ctrl+F to bring up the find box.
4. You should find a line with a href code href=”/en-US/firefox/downloads/file/35973/customizegoogle-0.75-fx+sm.xpi”

5. All you need to do is to add https://addons.mozilla.org infront of /en-US/firefox/downloads/file/35973/customizegoogle-0.75-fx+sm.xpi
6. The complete link would look like this.
https://addons.mozilla.org/en-US/firefox/downloads/file/35973/customizegoogle-0.75-fx+sm.xpi
Simply enter the full add-on link in the URL bar to download and install the add-on.

[tags]firefox, addon, plugin, extension, beta[/tags]