My wife posted on Reddit for me stating that I could not use Firefox since updating it to Firefox 65. I would always get "Your connection is not secure" "SEC_ERROR_UNKNOWN_ISSUER" on every website I try to visit. These include websites like Facebook, Google, and YouTube.
The responses started pouring in with other people having the same problem since the Firefox update. One solution was posted, however; and that was to turn off web shield in Avast.
I can browse the web with web shield disabled, but if I re-enable web shield, back to the same error every website.