Beta versions of Firefox 4 have been available for quite some time. A new version, Beta 12, was allowed to escape onto the internet last week and we’re very close to the launch of the final version. Mozilla QA are also using today to hold their Add-Ons Compatibility Testday event.
Being the Firefox fanatic that I am and having resisted the urge to make the move to Chrome, this week I downloaded Beta 12 to my work PC (having used various Beta versions on my home PC for some months and being satisfied it was safe to use for my activities in the office). I then set about testing all of my SEO add-ons ahead of the approaching final release to make sure they all still worked. Next week I’ll be reporting which add-on’s I’ve been using and how this went, but today I’ve decided to share with you how you can install your old add-ons into Firefox 4 Beta. I won’t be carrying out a full review of the new software as there are likely to be plenty of technology sites out there which will be publishing these over the next few weeks.
Installing Old Add-Ons
This is a question I see that crops up from time to time; if an add-on hasn’t been marked as compatible with the version of Firefox you’re using, how do you install it? If you had it installed and then updated, how do you enable it if it’s marked as no longer compatible?
Traditionally, I’ve always downloaded and hacked Firefox add-ons to make them install. You can also turn off compatibility checking, either by manually modifying some of Firefox’s hidden settings or installing the Add-On Compatibility Reporter. For the majority of times that I’ve tried this, my old add-ons work just fine or I only encounter a minor loss of functionality, however you should still proceed with caution. Bear in mind some add-ons will have been marked as incompatible for a reason, and forcing these to install could cause Firefox to crash if there are any major issues. If this happens, see the notes at the bottom of this post about starting Firefox in Safe Mode.
The ‘Hack’ Approach – Modify the Add-on
When installing an incompatible Firefox add-on, it’s quite easy to download and hack a Firefox add-on so it will install, and the majority of add-ons I’ve tested have run quite well. All you need is Notepad and the decompression/compression program 7-Zip.
Install 7-Zip first, and then browse to addons.mozilla.org to find the add-on you plan to use. If it hasn’t been marked as compatible with Firefox 4, the button will be greyed out:
You can’t install it, so right click ‘Add to Firefox’ and chose ‘Save Link As’. Save it to your desktop, to a place you can find it.
The file you’ve downloaded will have a ‘.xpi’ file extension and will essentially act as a compressed archive, much in the same way as ‘.zip’ files. Open the file using 7-Zip. You can usually do this by right clicking on the file, going to the 7-Zip context menu and selecting ‘Open Archive.’
You’re now browsing the files that make up your Firefox add-on. We aren’t going to change very much here – just look for a file marked ‘install.rdf’. Right click on this and select ‘edit’ which should launch the file in Notepad.
‘minVersion’ and ‘maxVersion’ define which versions of Firefox your add-on will run with, so find these lines and amend them by changing the maxVersion variable either to the version of Firefox you’re using or to something higher. You can use the * as a wildcard.
<em:minVersion>3.0</em:minVersion>
<em:maxVersion>4.*</em:maxVersion>
Save the file and close notepad. When you return to 7-Zip, you’ll be asked:
File ‘install.rdf’ was modified. Do you want to update it in the archive?
OK this message and your changes will be stored within the .xpi file. To install the modified add-on in Firefox 4, simply drag the .xpi file into the Firefox main window and follow the usual instructions.
Add-On Compatibility Reporter
Mozilla have also released the Add-On Compatibility Reporter which will allow you to enable disabled add-ons and lets you report back to Mozilla which of these work correctly. This means that if you’re upgrading from an earlier version of Firefox, some add-ons can be run that would otherwise be disabled due to incompatibility risks.
I’m told you can also install add-ons designed for earlier versions when using this tool, however I haven’t tried. If this is the case then this is almost certainly the easiest approach. If not, you can still use option #1 and modify the install.rdf file as detailed earlier.
The great thing about the Add-On Compatibility Reporter is that you can use this to let Mozilla know which add-ons do or do-not work. Simply go to Tools => Add-ons and choose an option from the ‘Compatibility’ menu.
Here Be Dragons! Disable Compatibility Testing in Firefox
If for any reason you don’t want/can’t use the Add-on Compatibility Tester, a way around this is to tinker with the settings and disabled compatibility checks.
Open Firefox, and in the address bar enter about:config. If Firefox were a car, you’re now opening the bonnet and about to tinker with the engine. However, remain cautious at all times as fire-breathing monstrosities roam in this area!
Proceeding with caution, you’ll now see a long list of variables. Those of you familiar with modifying the windows registry using regedit will probably feel quite comfortable here.
To begin with, let’s have a look at the compatibility settings that have already been applied. In the Filter, type extensions.checkCompatibility.
We are going to add to this list. Right click within the window, go to ‘New’ and select ‘Boolean’. Under ‘Preference Name’, type ‘extensions.checkCompatibility.4.0b’. A new row will appear, with the ‘Value’ set to ‘True’. Right click on this and select ‘Toggle’ to change it to ‘False’.
You can now enabled the add-ons that were disabled. I don’t recommend doing this with all of your add-ons in one go; if you enable them when at a time, should anything go wrong with one of the add-ons causing Firefox to continuously crash, at least with that approach you’ll know which it is and be able to disable it.
If it all goes wrong
While I was testing this, most of my add-ons worked without a problem, a small number no longer functioned at all, and one caused Firefox to crash, and also prevented me from accessing Tools => Add-ons to disable it. If this happens to you, you’ll need close Firefox and re-open it in Safe Mode. Using Safe Mode, your add-ons will be disabled and can safely access Tools => Add-ons to either permanently disable the offending item, or remove it completely.
In my next post, I’ll be running through my favourite SEO-related add-ons I’ve been using for the past couple of years and revealing which of these I found to be compatible with Firefox 4 Beta 12 and which have stopped working, so that you can make a decision about when you should upgrade.
If you fancy getting involved in the Add-Ons Compatability test day, don’t forget to read this blog about the event. We have also published a list of some of our favourite SEO Firefox Add-ons.
