Firefox add-on technology is modernizing
Add-ons are programs that add extra features to Firefox. Anyone can create an add-on and make it available to Firefox users who want to personalize their online experience.
In the past, add-ons often stopped working each time a new version of Firefox was released, because developers had to update them every six weeks to keep them compatible. To address this (and other issues), we overhauled the underlying technology for building add-ons.
Outside of rare instances, add-ons created with the new standard won’t break in new Firefox releases.
We recommend that you install add-ons with the “Compatible with Firefox 57+” label to ensure compatibility with Firefox beyond November 2017.
If you are the developer of a legacy add-on, resources are available to help you migrate to the new standard.