Most of our favorite add-ons still not updated to the latest Firefox 4. Instead of waiting for your add-on owners to update it,here is a simple tweak that will enable you to use your old incompatible add-ons o Firefox 4.
- Open Firefox 4.
- In the Address field, type about:config and hit Enter.
- Click on the disclaimer “I’ll be careful, I promise” button.
- Right-click and from the menu, select New and right after that Boolean.
- A new, small window will appear on your screen. Type in extensions.checkCompatibility.4.0 if you have Frefox 4.0.
- Click OK.
- When prompted select False and click OK.
- Restart your browser for the changes to take effect.
- Run and execute your old, incompatible addons!
You can use this trick in future releases as well. For example, once Firefox 5 will come, you just need to type “extensions.checkCompatibility.5.0” and set value to “false”.
Fix 2 : You can download the extension (the .xpi file) to your computer, unzip it and change the value of em:maxVersion under install.rdf file to 4.0.* –. Now pack the extension again and drag-n-drop to your Firefox browser.
Fix 3 : Install add-on named Compatibility Reporter. This add-on is developed by Mozilla itself, and it configures Firefox to work with incompatible add-ons.