SSLHandshakeException causes connections to fail

Indicates that a client connection was made to node01.example.com but the certificate returned did not contain the name node01.example.com. In most cases, the issue can be resolved by ensuring the name is specified during certificate creation. For more information, see Setting Up TLS on a cluster. Another scenario is when the environment does not wish to use DNS names in certificates at all. In this scenario, all settings in elasticsearch.yml should only use IP addresses including the network.publish_host setting.

Indicates that a client connection was made to an IP address but the returned certificate did not contain any SubjectAlternativeName entries. IP addresses are only used for hostname verification if they are specified as a SubjectAlternativeName during certificate creation. If the intent was to use IP addresses for hostname verification, then the certificate will need to be regenerated with the appropriate IP address. See Setting Up TLS on a cluster.

The SSLHandshakeException indicates that a self-signed certificate was returned by the client that is not trusted as it cannot be found in the truststore or keystore. This SSLException is seen on the client side of the connection.

This SunCertPathBuilderException indicates that a certificate was returned during the handshake that is not trusted. This message is seen on the client side of the connection. The SSLException is seen on the server side of the connection. The CA certificate that signed the returned certificate was not found in the keystore or truststore and needs to be added to trust this certificate.