Certificate name doesn't match
NET::ERR_CERT_COMMON_NAME_INVALIDThe hostname you visited isn't covered by the certificate's names, so the browser treats it as the wrong certificate.
What it means
A certificate is issued for a specific set of names listed in its Subject Alternative Name field. When you load a URL, the browser compares the hostname in the address bar against that list. If there's no match, you get NET::ERR_CERT_COMMON_NAME_INVALID. The certificate might be perfectly valid and well-trusted, but it was issued for a different name than the one you're using.
When it happens
This shows up when a certificate covers example.com but you visit www.example.com (or the reverse), when a wildcard cert for *.example.com is used on a bare apex domain it doesn't cover, or when several sites share an IP and the server hands back the wrong default certificate. It also happens right after a domain migration when the new hostname isn't on the cert yet.
How to fix it
- Reissue the certificate so it includes every hostname people actually use, including both the apex and the www variant.
- Remember that a wildcard like *.example.com covers subdomains but not the bare example.com, so add the apex explicitly if you need it.
- On servers hosting multiple sites, confirm Server Name Indication is configured so each hostname gets its matching certificate instead of a default one.
- After reissuing, verify the served certificate's name list matches the hostname before announcing the fix.
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Related errors
SSL_ERROR_BAD_CERT_DOMAINFirefox's name-mismatch error: the certificate doesn't cover the hostname you're visiting.
NET::ERR_CERT_AUTHORITY_INVALIDThe browser can't trace the certificate back to a trusted authority, which is what happens with self-signed certs or a missing intermediate.
NET::ERR_CERT_DATE_INVALIDThe certificate's validity dates don't line up with the current time, usually because it expired or the device clock is wrong.