AppleServiceException
System.Security.Authentication.AuthenticationException: A call to SSPI failed, see inner exception. ---> System.ComponentModel.Win32Exception: An unknown error occurred while processing the certificate
AppleServiceException
System.Security.Authentication.AuthenticationException: A call to SSPI failed, see inner exception. ---> System.ComponentModel.Win32Exception: An unknown error occurred while processing the certificate
It looks like a problem with your APNs certificate. Check if the certificate is valid. Ensure that you are using proper certificate for APNs (there are two types of certificate - 1. Development 2. Distribution).
Try looking at this SO question for more details.