Further extensions to the request are required for the server to fulfill it.A mandatory extension policy in the request is not accepted by the server for this resource.

The server must identify all mandatory extension declarations (both hop-by-hop and end-to-end); the server MAY ignore optional declarations without affecting the result of processing the HTTP message, and examine all extensions identified to determine if they are supported for this message. If not, respond with a 510.

This is a type of HTTP error. If you are registered with 100pulse, your site will be monitored and you will be intimated by an email or a short message service when 510 status code error occurs.