The issuer of the logout request message cannot be determined as a valid partner to this provider. On an identity provider, the request issuer must be a provider to which this provider has issued an assertion. On a service provider, the request issuer must be a provider that has issued an assertion to this provider.
System action
The operation will be halted.
Administrator response
If the request is legitimate, examine the trace logs to see why the request issuer was not found in the list of known logout partners.