Mozilla Firefox users started to notice that installed browser extensions were all disabled in the web browser suddenly. Extensions would display “could not be verified for use in Firefox and has been disabled” messages in the add-ons manager of the browser. Firefox would display “One or more installed add-ons cannot be verified and have been disabled” at the top as a notification next to that.

Some of the affected extensions include: IDM, LastPass, Ghostery, Download Manager (S3), Dark Mode, Honey, uBlock Origin, Greasemonkey, NoScript, and others.

Solution:
Download Firefox 66.0.4 Update (note it is not release, release candidate only)

Download Firefox 66.0.4 (Not Release)