If you run Firefox Nighly and use add-ons, you may have noticed that some may have been disabled automatically after the latest update of the browser.
When you open the add-ons manager, and then one of the add-ons that has been disabled automatically, a reason is displayed why it has been disabled.
The Dictionary Switcher add-on for instance displayed the following information: "Dictionary Switcher has been disabled since it is not multiprocess compatible".
Basically, what is happening is the following: if an add-on is neither a WebExtension nor multi-process compatible, it is disabled automatically in Firefox Nightly.
Note that this is limited to Nightly, and that other Firefox editions are not affected by this. This is however a foreboding of things to come, as the disabling of legacy add-ons will happen later this year when Firefox 57 gets released to the public.
Mozilla reveals the reason behind the move on the Mozilla Wiki.
The Firefox team is currently focused on vastly improving performance in Firefox 57. Unfortunately, if you have add-ons installed in Nightly that are not WebExtensions, they make performance measurements on Nightly much harder. This is especially true of add-ons that are not multiprocess compatible and use shims.
As a result, we are asking all Nightly users to stop using add-ons that are not multiprocess compatible, or are not WebExtensions. Please bear in mind that these add-ons might stop working by Firefox 57 anyway.
Fix for disabled add-ons in Firefox Nightly
You probably wonder if there is something that you can do about it. And there is, at least for the time being.
- Load about:config in the Firefox Nightly address bar.
- Confirm that you will be careful if the prompt comes up.
- Search for the preference extensions.allow-non-mpc-extensions.
- Double-click it to set it to true.
The add-ons that were disabled automatically after the Nightly update will be enabled on the next restart again once you set the preference to true.
Keep in mind that this preference will be removed in the future, likely around the time that Mozilla will drop support for legacy add-ons. You can follow the tracking bug 1352204 to monitor the development.
Mozilla states clearly that it implemented the change to get better performance telemetry data. It seems likely that the organization is also keeping an eye on things for another reason: it is a first test balloon to see how Nightly users will react. How many will accept the change, how many will reverse it using the preference, and how many will switch to another version of Firefox or another browser?
Now You: How many of your add-ons would be disabled if you'd run Nightly?