If you’re like me, you probably lost a few extensions during the upgrade to Firefox 3 because the original author simply disappeared and never updated his extensions, or perhaps you came up against a problem and all the solutions seem to point towards an extension incompatible with Firefox 3.
In either case, it’s very annoying not to be able to install or use the extensions that you want/need. This is when disabling the add-on compatibility check comes in handy. All it takes is adding one entry into your about:config, which I’ll show you in the video/steps below.
1. Go to about:config
2. Right click > new > boolean
3. Set the preference name to extensions.checkCompatibility and the value to false
4. Restart Firefox.
And there you go! No more extension compatibility checks. To make sure it’s working look for the warning that appears in your add-ons manager. I used this to allow me to install both Snaplinks and MIME edit.
Alternatively, you can install the Nightly Tester Tools extension and use its Force Install feature if you’re uncomfortable editing your about:config.