Hi Mike, which warning are you getting? Classically, there are two full page errors that can appear and prevent access to sites: Secure connection failed and Firefox did not connect. Is it one of those?

If you get a page with an Advanced button, that should provide access to more technical information including an error code (often SEC_ERROR_SOMETHING). The following article summarizes the most common codes: How to troubleshoot security error codes on secure websites. Or of course let us know what code(s) you are getting.

I need to disable this whole security function. I us my own choice of security software for this purpose. this feature is neither wanted nor acceptable. I need to turn this function off completely or disable it. Firefox is starting to behave more like Microsoft Edge. Please advise ASAP. Thanx, Mike

You cannot disable verification of site certificates in Firefox. If this affects a lot of \sites, you probably have a "man in the middle" that you can set Firefox to trust, assuming the impostor is trustworthy.

If you click that View Certificate button, who is listed as the issuer of the certificate? When I check that site, it says:

Issuer Name Common Name GlobalSign Organization Validation CA - SHA256 - G2

How about yours? Check other sites and see whether there is a pattern pointing to a known intermediary.

Who is the issuer of the certificate ?

You can check details about the issuer of the certificate and the certificate chain.

• click the "Advanced" button on the error page to show more detail
• click the blue "View Certificate" text to inspect the certificate chain in the Certificate Viewer