This ProxySQL post is sourced from an error I faced recently handler___status_CONNECTING_CLIENT___STATE_SERVER_HANDSHAKE(): [ERROR] ProxySQL Error: Access denied for user ProxySQL has become one of the popular choice as the “proxy” for MySQL databases. This post is tipping you off for debugging connectivity issue and fixtures around it for a specific use-case. ProxySQL Connectivity Ofcourse while to connect ProxySQL we have two choices for what we want to do: Admin Interface and MySQL. Admin interface allows us to configure and manage the ProxySQL. MySQL interface is basically the “proxy” connectivity to MySQL databases configured in ProxySQL.