[FIXED] Certificate issue causing add-ons to be disabled or fail to install:

May 5, 2019:

We released Firefox 66.0.4 for Desktop and Android, as well as Firefox 60.6.2 ESR that re-enables extensions. For more information, please read the update on https://blog.mozilla.org/addons/2019/05/04/update-regarding-add-ons-in-firefox

Thank you for being patient with us! Thanks to everyone working on it!

May 14, 2019:

If you are running Firefox 52 - 56 , you can install this extension to fix the expired certificate issue and re-enable your extensions and themes.

For Firefox versions 57 - 60, please install this extension to fix the issue.

If you are running Firefox versions 61 – 65 and 1) did not receive the deployed fix and 2) do not want to update to the current version (which includes the permanent fix): Install this extension to resolve the expired security certificate issue and re-enable extensions and themes.

This wraps up our planned deployments; if you continue to experience problems related to the expired certificate issue, please post on our forum and we will do our best to help you out.