Firefox 57 is now on the Nightly channel (along with a shiny new logo!). And while it isn’t disabling legacy add-ons just yet, it will soon. There should be no expectation of legacy add-on support on this or later versions. In preparation for Firefox 57, a number of compatibility changes are being implemented on addons.mozilla.org (AMO) to support this transition.
Upcoming Compatibility Changes
- All legacy add-ons will have strict compatibility set, with a maximum version of 56.*. This is the end of the line for legacy add-on compatibility. They can still be installed on Nightly with some preference changes, but may break due to other changes happening in Firefox.
- Related to this, you won’t be able to upload legacy add-ons that have a maximum version set higher than 56.*.
- It will be easier to find older versions of add-ons when the latest one isn’t compatible. Some developers will be submitting ports to the WebExtensions API that depend on very recent API developments, so they may need to set a minimum version of 56.0 or 57.0. That can make it difficult for users of older versions of Firefox to find a compatible version. To address this, compatibility filters on search will be off by default. Also, we will give more prominence to the All Versions page, where older versions of the add-on are available.
- Add-ons built with WebExtensions APIs will eventually show up higher on search rankings. This is meant to reduce instances of users installing add-ons that will break within a few weeks.
We will be rolling out these changes in the coming weeks.
Add-on compatibility is one of the most complex AMO features, so it’s possible that some things won’t work exactly right at first. If you run into any compatibility issues, please file them here.