The Federation Service encountered an error while loading the trust policy. An account partner that does not have Windows ...

The Federation Service encountered an error while loading the trust policy. An account partner that does not have Windows trust enabled is configured to allow all user principal name (UPN) suffixes. 

If this error occurs during startup of the Federation Service, the Federation Service will be not be able to start, and all requests to the Federation Service will fail until the configuration is corrected. If this error occurs while the Federation Service is running, the Federation Service will continue to use the last trust policy that was loaded successfully. 

User Action 
This error should occur only if the trust policy file has been modified without use of the AD FS administrative tools. Account partners that do not have Windows trust enabled must provide an explicit list of UPN suffixes for validation. Add at least one UPN suffix for this account partner.