Add-ons disabled or fail to install on Firefox

On late Friday, May 3rd, we became aware of an issue with Firefox that prevented existing and new add-ons from running or being installed. We are very sorry for the inconvenience caused to people who use Firefox.

Our team has identified and rolled-out a fix for all Firefox Desktop users on Release, Beta and Nightly. The fix will be automatically applied in the background within the next few hours. No active steps need to be taken to make add-ons work again.

To deliver a fix on short notice, we are using the Studies system. This system is enabled by default, and no action is needed unless Studies have been disabled. Firefox users can check if they have Studies enabled by going to:

1. In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button and select Settings.
2. Click Privacy & Security on the left panel.
3. Put a check mark next to Allow Firefox to install and run studies (scroll down to find this setting).

   

   Studies can be disabled again after the add-ons have been re-enabled.

It may take up to six hours for the study to be applied to Firefox. To check if the fix has been applied, you can enter about:studies in the address bar. If the fix is active, you’ll see hotfix-reset-xpi-verification-timestamp-1548973 as shown:

You may also see hotfix-update-xpi-signing-intermediate-bug-1548973 listed, which is part of the fix and may be in the Active or Completed section.

We are working on a general fix that doesn’t use the Studies system and will keep this blog post updated accordingly.

We will share a more substantial update in the coming days.