Firefox 50 will be released on November 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 50 for Developers, so you should also give it a look.

General

XPCOM and Modules

New

Provide API for add-ons to delay restartless updates. Delaying updates can be useful if an add-on is in the middle of running a slow process that needs to run completely.

Let me know in the comments if there’s anything missing or incorrect on these lists. If your add-on breaks on Firefox 50, 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 49.