Firefox Add-ons Disabled and Can’t Download new Add-ons

When you open Firefox, you may be surprised to see that all of your add-ons are disabled and you’re unable to install new add-ons. This is caused by an expired certificate used to sign Mozilla add-ons.

When you try to install a new add-on, you’ll see the error “Download failed. Please check your connection

And Mozilla team already started rolling out a fix.

Latest Official Updates:

12:50 p.m. UTC / 03:50 a.m. PDT: We rolled-out a fix for release, beta and nightly users on Desktop. The fix will be automatically applied in the background within the next few hours, you don’t need to take active steps.

In order to be able to provide this fix on short notice, we are using the Studies system. You can check if you have studies enabled by going to Firefox Preferences -> Privacy & Security -> Allow Firefox to install and run studies.

You can disable studies again after your add-ons have been re-enabled.

We are working on a general fix that doesn’t need to rely on this and will keep you updated.

~ Andreas Wagner, Add-ons Technical Editor

firefox add-ons disabled

Certificate issue causing add-ons to be disabled or fail to install – Add-ons / Announcements – Mozilla Discourse

We have rolled out a partial fix for this issue. We generated a new intermediate certificate with the same name/key but an updated validity window and pushed it out to users via Normandy (this should be most users). Users who have Normandy on should see their add-ons start working over the next few hours. We are continuing to work on packaging up the new certificate for users who have Normandy disabled.

Summary: Firefox marked addons due signing as unsupported, but doesn’t allow re-downloads from AMO → All extensions disabled due to expiration of intermediate signing cert


Firefox enforces the use of signatures by default. But has a preference that allows signature enforcement to be disabled (xpinstall.signatures.required in about:config). Firefox checks for verified signature on add-ons and extensions. You can disable the add-on signature enforcement temporarily, until Mozilla fixes the issue. This lets you install add-ons and extensions without any problem.

To disable Add-On signature verification:

  1. Open the about:config page in Firefox
  2. In the Search box type xpinstall.signatures.required
  3. Set xpinstall.signatures.required flag to false.
    firefox add-ons disabled

This allows you to install new Add-ons and use enable/existing add-ons.

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About the author

Ramesh Srinivasan founded back in 2005. He is passionate about Microsoft technologies and he has been a Microsoft Most Valuable Professional (MVP) for 10 consecutive years from 2003 to 2012.

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