While trying to make a WCF service to connect Dynamics 365, I came across to this error message:
Message Metadata contains a reference that cannot be resolved: ‘https://dynamics.com/test.svc?wsdl&sdkversion=9’. >> StackTrace at System.ServiceModel.Description.MetadataExchangeClient. MetadataRetriever.Retrieve(TimeoutHelper timeoutHelper)\r\n
We also saw the error below during testing:
InnerException System.Net.WebException: Unable to connect to the remote server —> System.Net.Sockets.SocketException: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond
Root Cause
Dynamics 365 started requiring TLS 1.2 after version 9.x (Reference). Connections that don’t use TLS 1.2 started failing after this update.
Solution
Force WCF service to use TLS 1.2 to solve this issue. One way of forcing it is to use the following line in the application:
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;