Mozilla has confirmed via Twitter that it has automatically disabled all Firefox browser extensions and apologized: “Sorry for the problem we’re having with add-ons now! We’re working hard to fix it and keep you posted.”
According to the bugzilla report, an intermediate signature certificate used to sign Mozilla extensions expired on 04/05/19 at midnight UTC. Because Mozilla extensions must be signed before they are used in Firefox, as soon as the computer’s timing reaches this time, the browser automatically disables them.
If extensions are not important to you, you can wait for Mozilla to fix the problem and the extensions will start working again. For those who do not want to wait and want to activate installed extensions right away, you have some options:
- Put your watch back a few days
- Or install Firefox Nightly versions
Source : Mozilla (Tweet)