Firefox extension compatibility

From time to time I like checking out the bleeding edge version of  some software. Firefox is always a good candidate for that, because of the many improvements in performance and features. I downloaded the Firefox 3.7a nightly build from It’s seems pretty stable on my computer and is obviously faster. Sunspider tests confirm my expectations of increased javascript performance which is roughly 40% faster than Firefox 3.5.5 on my machine.  Though if your mostly considered with javascript performance then it’s best you try Chrome (beta) which using the same tests seems to be 60% faster than Firefox 3.5.5. Performance is all and good, but when using the newest Firefox version a lot of extensions that I need are tagged as not compatible, which makes sense as they were not yet tested. Even though most of them could work if not for the version limitations in the extension installation descriptor. I’m writing this post because I was trying to change the version of an extension I needed, but restarting the browser didn’t seem to help and I couldn’t get it working, but I remember that I have done this in the past. So this is to remind myself that after extension descriptor modifications you need to delete the extensions.cache file in your Firefox profile folder. I’m not going to get into the details of how I do it, because I found a good write up with three ways of making old extensions work.  It’s written for the Firefox 2, but it still applies to new versions. I haven’t tested the first two methods since I always done it the third (apparently the hard) way.