In Firefox 48, which reaches the release channel on August 1, 2016, mullti-process support (code name “Electrolysis”, or “e10s”) will begin rolling out to Firefox users without any add-ons installed.

In preparation for the wider roll-out to users with add-ons installed, we have implemented compatibility checks on all add-ons uploaded to addons.mozilla.org (AMO).

There are currently three possible states:

1. The add-on is a WebExtension and hence compatible.
2. The add-on has marked itself in the install.rdf as multi-process compatible.
3. The add-on has not marked itself compatible, so the state is currently unknown.

If a new add-on or a new version of an old add-on is not multi-process compatible, a warning will be shown in the validation step. Here is an example:

In future releases, this warning might become more severe as the feature nears full deployment.

For add-ons that fall into the third category, we might implement a more detailed check in a future release, to provide developers with more insight into the “unknown” state.

After an add-on is uploaded, the state is shown in the Developer Hub. Here is an example:

Once you verify that your add-on is compatible, be sure to mark it as such and upload a new version to AMO. There is documentation on MDN on how to test and mark your add-on.

If your add-on is not compatible, please head to our resource center where you will find information on how to update it and where to get help. We’re here to support you!

https://blog.mozilla.org/addons/2016/06/17/multi-process-firefox-and-amo/