Bug in latest Firefox 65 update blocks HTTPS websites
Firefox version 65 was intended to provide users with an improved browsing experience by providing simplified content blocking controls, WebP image support, more privacy setting options and AV1-format support. However upon installing, the Firefox 65 update seems to do the contrary. Users reported experiencing problems visiting HTTPS websites, which appear to clash with certain antivirus programs; such as Avast, AVG and Kaperasky.
In these cases the users received the error notifications "Your connection is not secure" and “SEC_ERROR_UNKNOWN_ISSUER”; as all HTTPS Connections were mistakenly blocked by Firefox. Early troubleshooting strategies have surfaced online and involve either manually deactivating HTTPS scanning or authorizing Firefox to accept Windows certificates. The antivirus manufacturers have also started working on resolving the issue on their end.
Mozilla itself has published a bug report protocol for the bug, but is yet to release an official statement on the problem; instead they pulled the brakes on the version 65 Rollout making it unclear when the issue will be resolved.