firefox os x your connection is not secure every website

The solution depends on your confidence that the error is spurious, which depends on how much trust you can put into that address and site. It may appear sporadic, although once it has affected a site, Safari is unlikely to be able to make that connection properly again. This can affect any (reasonably recent) version of Safari, running on macOS, iOS or iPadOS, and on pretty well any version of those operating systems. That Safarian error message means that it tried to connect using HTTPS, and has detected a certificate problem. You try to connect to an affected website using Safari, only to be informed that This Connection Is Not Private.

And there’s more than one certificate which has now expired. Unfortunately, it has turned out that this isn’t confined to older Mac OS X, and can even affect Monterey betas. A few days ago I warned that those still using older versions of Mac OS X are likely to have problems making secure HTTPS connections with many websites, because of a security certificate due to expire on 30 September.

Firefox os x your connection is not secure every website