It is easy to understand why: Over the past few years, third-party developers have devised hundreds of useful, and often ingenious, ways to adopt Firefox to suit their needs. If it is physically possible for Firefox to do something, chances are somebody has created an extension that can do it. Over the years, Firefox extensions have combined to create something that no software company of any size could have created -- or even envisioned -- on its own.
As you can imagine, however, ensuring that hundreds of third-party applications work with every new Firefox update is a tall task. In order to ensure that out-of-date extensions don't cause problems for Firefox users, Mozilla has built a compatibility-checking system into Firefox. Extensions are approved only for a certain set of Firefox releases; those that work with Firefox 2.x, for example, will not automatically work with any version 3.x release.
In many cases, an extension that works with the current Firefox release will work just as well on future releases. Just in case they don't, however, Mozilla's compatibility-checking system forces developers to take responsibility for testing -- and, if necessary, for fixing -- their extensions before they will work with a new version of Firefox.
This is an essential process, but it has a downside. As recently as last month, for example, the final Firefox 3 beta was incompatible with a long list of popular Firefox extensions. That is fine as long as a new Firefox release is still in beta testing and thus best left in the hands of developers and dedicated testers. Once a new release hits release candidate status, however, many Firefox users get distinctly uneasy when their favorite extensions still are not compatible -- and they get even more upset when developers fail to tell anyone what, if anything, they are doing to get their extensions ready for an update.
(There are ways for developers and experienced Firefox users to override the compatibility checks and to force older extensions to work with a new browser release. Generally, a little research will tell you whether it is safe to force an extension to work with Firefox 3. Just remember that there are two types of Firefox users who attempt this trick: those who back up their Firefox profiles regularly, and those who enjoy making life difficult for themselves.)
Recently, this was precisely the issue that had many users concerned about the upcoming Firefox 3 release: Too many developers still had not issued compatibility updates for their extensions.
Over the past couple of weeks, however, a steady stream of Firefox extension updates has turned into a flood. This was due mostly to Mozilla's release of a Firefox 3 release candidate; at this point, Mozilla could assure extension developers that it would also approve their compatibility updates for the final Firefox 3 release. Although some extension developers issued multiple updates during the Firefox 3 pre-release process, the vast majority wanted to avoid the hassle of going through the process more than once -- even when, in many cases, their compatibility updates have long been ready and waiting.
If you have any concerns about your favorite Firefox extensions, there are a couple of blogs with a wealth of good information on the topic. First, check out Alex Polvi's "State of the Add-Ons Report," which tracks the compatibility status of many popular Firefox extensions. At this point, even when an extension is not yet officially compatible with Firefox 3, many developers are at least providing status reports on their work -- and, in a handful of cases, asking for help squashing compatibility-related bugs.
Another great resource is Deb Richardson's blog entry tracking 20 of the top Firefox extensions that are now officially compatible with Firefox 3. As with Alex Polvi's report, Richardson's blog entry also includes a wealth of information in the reader comments, many of which provide information about the compatibility status of other well-known extensions.
Finally, if you and your business don't use Firefox, a visit to addons.mozilla.org just might convince you to give it a try. This is the official home of approved third-party Firefox extensions -- and if I had to name the single most important factor behind Mozilla's continuing success, this definitely would be my pick.