src:http://devlicio.us/blogs/brendantompkins/archive/2007/11/20/getting-firebug-to-work-with-firefox-3-beta-1.aspx

Getting FireBug to work with FireFox 3 Beta 1

Just grabbed my copy of FireFox 3 Beta 1 today.. After installation, most of the extensions that I’ve come to rely on aren’t working, which is understandable. One extension, FireBug, is a tool that I simply cannot work without. It’s the best tool I’ve ever found for debugging HTML, CSS, HTTP and JavaScript, bar none. If you’re a web developer working without it, you may find that you’re spending way more time than you have to debugging browser issues.

The problem is, when I tried to install it under FF3, I got the message that it would not run… Here are the steps I took to fix this.

1. Saved the firebug-1.05-fx+fl.xpi file to disk
2. Re-named it to firebug-1.05-fx+fl.zip
3. Opened the zip file, and extracted the file “install.rdf”
4. Opened “install.rdf” with Notepad
5. Changed <em:maxVersion>2.0.0.*</em:maxVersion> to <em:maxVersion>3.0.0.*</em:maxVersion>
6. Saved the file, and replaced the version in the zip file with the new version
7. Renamed the .zip file back to firebug-1.05-fx+fl.xpi
8. Drag-drop firebug-1.05-fx+fl.xpi into an instance of FF3.

Voila! I have FireBug with FF3! You can also try this with other extensions, but your mileage may vary.

-Brendan