Mozilla plans to launch Firefox 4.0 on March 22, 2011. The news comes straight from the horse's mouth: the new release date was posted on the Mozilla Wiki and on

Mozilla has found problems in the current RC1 build, but it has decided that those issues aren't critical. RC1 will be released as the final version and a 4.0.1 release will be issued instead. The company will enable users to update Firefox versions 3.5 and 3.6 to 4.0 without the need to navigate to a download page.

Mozilla was originally planning on having Firefox 4 out by the end of last year, but it has had to delay the release multiple times. The company has fixed more than 7,000 bugs in the 12 betas. Last week, the company put out an RC build and now all that's left is the final release.

Mozilla has been struggling to get Firefox 4.0 out the door. As a result, the company has announced that in 2011, not only will we see Firefox 4.0, but we will also see Firefox 5.0, Firefox 6.0, and Firefox 7.0. The first 5.0 builds are already in the making; the next version is targeted for a late June 2011 release.


Firefox 4 RC1 has received a very warm welcome; it's time to make a decision to ship. As of now, there are no known issues that would stop us from shipping RC1 as final. At the conclusion of our regular 11:30AM triage session on Wednesday, March 16th, release drivers will decide whether to ship RC1 as Firefox 4.

March 22nd is the day we would ship. Both IT and Marketing have indicated that March 22nd is an acceptable final launch date. If at any time we discover issues that would block final release, we would issue an RC2 as soon as possible, reset the ship date, and communicate to everyone.

All my best,