Firefox 55 will be released on August 8th. Here’s the list of changes that went into this version that can affect add-on compatibility. There is more information available in Firefox 55 for Developers, so you should also give it a look. Also, if you haven’t yet, please read our roadmap to Firefox 57.

General

Recently, we turned on a restriction on Nightly that only allows multiprocess add-ons to be enabled. You can use a preference to toggle it. Also, Firefox 55 is the first version to move directly from Nightly to Beta after the removal of the Aurora channel.

XPCOM and Modules

Let me know in the comments if there’s anything missing or incorrect on these lists. We’d like to know if your add-on breaks on Firefox 55.

The automatic compatibility validation and upgrade for add-ons on AMO will happen in a few weeks, so keep an eye on your email if you have an add-on listed on our site with its compatibility set to Firefox 54.