Port your user data
If your legacy add-on stores user data, we encourage you to take advantage of Embedded WebExtensions to transfer the data to a format that can be used by WebExtensions. This is critical if you want to seamlessly migrate your users—without putting any actionable burden on them—to the new WebExtensions version when it’s ready. (Embedded WebExtensions is a framework that contains your WebExtension inside of a bootstrapped or SDK extension.)
Testing beta versions
If you want to test a WebExtensions version of your add-on with a smaller group of users, you can make use of the beta versions feature on addons.mozilla.org (AMO). This lets you test pre-release beta versions that are signed and available to Firefox users who want to give them a spin. You’ll benefit from real users interacting with your new version and providing valuable feedback—without sacrificing the good reputation and rating of your listed version. We don’t recommend creating a separate listing on release because this will fragment your user base and leave a large number of them behind when Firefox 57 is released.
Don’t leave your users behind
Updating your listing on AMO when your WebExtension is ready is the only way to ensure all of your users move over without any noticeable interruption.
Need further assistance with your migration journey? You can find real-time help during office hours, or by emailing webextensions-support [@] mozilla [dot] org.