Firefox is currently transitioning to a multiprocess architecture (e10s), which will give users a more stable and responsive browser. This transition affects certain add-ons, which must adapt to the new model or they won’t work correctly, and will be flagged as incompatible. We’re reaching out to add-on developers in various ways so they can check whether their add-ons are affected, and get support for updating their add-ons.

Now, there’s a way for you to help as well with outreach efforts, and that is by reporting incompatible add-ons.

Add-on Compatibility Reporter (ACR) enables you to tell us if an add-on works in a particular version of Firefox. Its reports have been a very useful tool for us in tracking incompatible add-ons and helping developers fix them. Add-on developers are also able to see reports sent for their add-ons in the developer tools. If you want to give it a try, we suggest that you do on one of the prerelease versions: Beta, Developer Edition, or Nightly. The latter two have multiprocess enabled for all add-ons by default, which is what we’re most interested in at the moment.

The latest versions of ACR have integrated support for multiprocess Firefox. Once you install the add-on, you will see which of your add-ons have declared multiprocess compatibility. You will also see if your version of Firefox has multiprocess enabled. The icons let you report if an add-on works or not.

You can also do all of this from the Add-ons Manager, if you prefer.

To determine if an add-on is multiprocess compatible, ACR looks for a flag in the add-on manifest, set by the developer. So, for example, Password Exporter appears as not compatible, even though it works correctly with e10s on. I maintain Password Exporter and haven’t yet updated its manifest to reflect this (I will soon!).

Knowing which add-ons are working with e10s is critical for a successful transition, so we hope you can help us by installing the Add-on Compatibility Reporter and letting us know which add-ons aren’t working for you.