If you have been using Selenium as part of your continuous build process, then the release of Firefox 3 has probably caused you some problems – specifically the inability to have Firefox 3 launch with the custom profile to allow Selenium to run.

It turns out Selenium installs a tiny little extension into the Firefox profiles it generates that basically just lets selenium kill firefox by telling it to go to a magic chrome url. Firefox extensions specify which versions they are compatible with and the one embedded in selenium had 2.0.0.* as their maximum version…

It looks like the solution is actually very simple and is described in detail over at Space Vatican.