I realise there have been a number of similar posts to this but I haven\'t found a solution yet. Am trying to post some xml to an MPI gateway but keep getting the following
I think its because you are connecting to "https" url. In this case you have to add following line to your code.
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
It will accept "ssl" protocol for your request. "ServicePointManager.ServerCertificateValidationCallback" handler just controls certificate validity.
Slightly better perhaps:
System.Net.ServicePointManager.SecurityProtocol = System.Net.ServicePointManager.SecurityProtocol | System.Net.SecurityProtocolType.Tls12;