The Federation Service failed a privileged Web method call because Secure Sockets Layer (SSL) client authentication information ...

The Federation Service failed a privileged Web method call because Secure Sockets Layer (SSL) client authentication information was not available. 

This event can occur if the client does not provide a client certificate or if Internet Information Services (IIS) rejects the client's certificate because it does not chain to a trusted root certification authority in the Federation Service. 

User Action 
If this is a valid call from the Federation Service Proxy, ensure that the root of the Federation Service Proxy client certificate is trusted by the Federation Service.