high

NET::ERR_CERT_COMMON_NAME_INVALID

Domain name doesn't match any domain in the SSL certificate.

Common Causes

  1. 1Certificate issued for different domain
  2. 2www vs non-www mismatch
  3. 3Wildcard cert doesn't cover sub-subdomains

How to Fix

Include all domains

sudo certbot --nginx -d example.com -d www.example.com -d api.example.com

Include all domains and subdomains in the certificate.

How ObserveOne Helps

A name mismatch fails the TLS connection itself. Pointing an ObserveOne check at each hostname you serve catches a certificate that quietly stops covering one of them.

Start Monitoring Free

Related Errors

NET::ERR_CERT_AUTHORITY_INVALID

SSL certificate is not signed by a trusted Certificate Authority.

NET::ERR_CERT_DATE_INVALID

SSL certificate has expired or is not yet valid.

ERR_SSL_PROTOCOL_ERROR

The browser cannot establish a secure SSL/TLS connection because the server and browser cannot agree on a protocol version or cipher suite.

ERR_SSL_VERSION_OR_CIPHER_MISMATCH

Server and browser cannot agree on SSL/TLS protocol version or cipher suite.

SSL Handshake Failed

SSL/TLS handshake between client and server failed to complete.