Last week Mozilla halted the rollout of Firefox 65 for Windows after users started reporting insecure certificate errors due to antivirus software conflicts. Avast created a hotfix that disabled SSL scanning for the Firefox process in Avast and AVG. Mozilla QA lead Ryan VanderMeulen has stated that they have enabled the update again now that they are seeing less errors ever since the antivirus programs disabled their HTTPS scanning for Firefox process. The Avast director of engineering Luk . Ryp .ek commented in the bug ticket that a better way needs to be developed.
Source: https://www.bleepingcomputer.com/news/software/mozilla-resumes-firefox-65-rollout-after-avs-disable-https-scanning/