"System error trying to perform entity import." error is popping up whenever attempting to import a Metadata that contains AttributeService
if AttributeService is being used , you need to check if AttributeService Binding contains a supported binding protocol .
Per SAML specification guide Section 6.3.1 Query/Request issued by SAML Requester , The SAML requester MUST use a synchronous binding, such as the SOAP binding [SAMLBind]
Siteminder supports SOAP binding for AttributeService.
In case the below for example was sent in the Metadata , the Import will fail from Administrative UI with error "System error trying to perform entity import."
<AttributeService Binding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect" Location="https://one.ca.com/6033"/>