With the switch to the rapid release cycle came an interesting problem for Mozilla, one that creeped up only occasionally for the group, add-on compatibility. With each major release, add-on developers had to update their creations to ensure they still worked.

But with new versions coming out every six weeks, that's now unfeasible, which is why add-ons will be automatically marked as compatible unless they fail certain tests or meet certain criteria.

With the release of Firefox 5 Beta, Mozilla updated add-ons that were designed for Firefox 4 to also work in Firefox 5, more specifically for users to be able to install them from the add-on repository.

"We updated compatibility information for add-ons that work with Firefox 4 to also work with Firefox 5, except in certain cases where we think the add-on may be incompatible," Mozilla announced.

"We were able to mark 3,890 add-ons as compatible with Firefox 5. There were 256 that failed our automatic scanners either due to including binary components or using navigator.language, which was changed in Firefox 5," it added.

This is the first time Mozilla updated the compatibility of add-ons in bulk, so issues may have popped up. From the first sings, though, things went smoothly.

Normally, once Mozilla has completely switched to the rapid release cycle, add-ons will be updated once a Firefox version moves to the Aurora channel, from the Nightly one. Next up in the Aurora channel is Firefox 6 which should be offered as an update to Firefox 5 Aurora users soon.

However, it is likely that only starting with Firefox 7 add-ons will be updated when the switch to Aurora is made.

In this first batch, add-ons that failed the automated test and those that used an API which was changed in the latest release were labeled as incompatible, the rest can now be installed in Firefox 5 from Mozilla Add-ons.