Mozilla has halted the automatic updates to Firefox 65 as users are unable to browse web sites due to certificate errors. These errors are being caused by conflicts between antivirus programs’ HTTPS scanning and Firefox 65. Avast & AVG products will be disabling HTTPS scanning for the Firefox process in the next few hours until a proper fix can be created. Firefox 65 will use only use certificates in their built in browser certificate store. It is possible to enable Firefox to use certificates created in the Windows certificate store to validate other web sites certificates.
Source: https://www.bleepingcomputer.com/news/software/mozilla-halts-firefox-65-rollout-due-to-insecure-certificate-errors/