If you haven’t yet, please read our roadmap to Firefox 57.
Firefox 54 will be released on June 13th. Here’s the list of changes that went into this version that can affect add-on compatibility. There is more information available in Firefox 54 for Developers, so you should also give it a look.
-moz-appearance. This doesn’t apply to CSS sheets loaded using a
XPCOM and Modules
- Don’t allow empty host name for
URLTYPE_AUTHORITY URLs. This affects add-ons that use
nsIContentPolicyto redirect certain requests (a practice that isn’t recommended, but some add-ons are known to use it).
- Remove token arguments from
sessions.restorereturns an array instead of an object. The return value is now an object, matching what the equivalent Chrome API does.
onConnectExternal. Quoting comment 34, this changes the meaning of the
browser.runtime.idproperty, which may cause issues for extensions which expect that to be the same as the ID used in their URLs.
webRequestdoesn’t check host permissions. You’ll need to add the necessary permissions for
webRequestto continue working. At the moment this is incompatible with the Chrome API.
Let me know in the comments if there’s anything missing or incorrect on these lists. If your add-on breaks on Firefox 54, I’d like to know.
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 53.