The SAML message is required by the specification to have an Issuer attribute. The Issuer format, if specified, must be urn:oasis:names:tc:SAML:2.0:nameid-format:entity. The message is either missing the Issuer attribute or has the wrong format specified.
System action
The message will be ignored.
Administrator response
Examine the trace logs on the provider that issued the message to see why the message was constructed without the Issuer attribute or with the incorrect Issuer format.