My computer is running macOS version "10.14.5 (18F132)". I'm testing in Chrome version "75.0.3770.142 (Official Build) (64-bit)". Chrome was updated recently, i.e. yesterday, from an unknown earlier version (tho fairly recent I think).

Several days ago mkcert seemed to be working as expected. Today I get the error mentioned in the title.

I was able to get it working again by manually adding the certificate to my "login" "Certificates" in the Keychain Access app by following the steps in this answer to the following Super User question:

• ssl - How do I deal with NET:ERR_CERT_AUTHORITY_INVALID in Chrome? - Super User

This might be related to this recently opened issue:

• "Certificate is not standards compliant" on macOS Catalina · Issue #174

Please say more about how you're doing your testing @daquinoaldo - and this is mkcert v1.4.0 true?

BTW, I'm quite sure this is a dup of https://github.com/FiloSottile/mkcert/issues/174 and this one should be closed.