Error: "Subject Alternative Name Missing" or NET::ERR_CERT_COMMON_NAME_INVALID or "Your connection is not private"

During Transport Layer Security (TLS) connections, Chrome browser checks to make sure the connection to the site is using a valid, trusted server certificate.

For Chrome 58 and later, only the subjectAlternativeName extension, not commonName, is used to match the domain name and site certificate. The certificate subject alternative name can be a domain name or IP address. If the certificate doesn’t have the correct subjectAlternativeName extension, users get a NET::ERR_CERT_COMMON_NAME_INVALID error letting them know that the connection isn’t private. If the certificate is missing a subjectAlternativeName extension, users see a warning in the Security panel in Chrome DevTools that lets them know the subject alternative name is missing.

Some public key infrastructures (PKIs), legacy systems, and older versions of network monitoring software use certificates without subjectAlternativeName extensions. If you’re having issues with any of these, contact the software vendor or administrator and ask them to generate a new certificate.

For Microsoft® Windows®, you can use the PowerShell Cmdlet New-SelfSignedCertificate and specify the DnsName parameter.

For OpenSSL, you can use the subjectAltName extension to specify the subject alternative name.

If needed, until Chrome 65, you can set the EnableCommonNameFallbackForLocalAnchors policy. This lets Chrome use the commonName of a certificate to match a hostname if the certificate is missing a subjectAlternativeName extension.

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