A Call To SSPI Failed, See Inner Exception - The Local Security Authority Cannot Be Contacted
Answer : This means the other side is using another version of TLS and you are using an older version. Set up security attribute to TLS12 before making the connection. This is a widely known problem, as many providers start using TLS12 (e.g. paypal,amazon and so on). ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12; Here is the solution, set in the registry: [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\KeyExchangeAlgorithms\Diffie-Hellman] "ClientMinKeyBitLength"=dword:00000200 as noted here If you are using SslStream, then you need to explicitly set the TLS version in the AuthenticateAsClient call, for example: ssl.AuthenticateAsClient(url, null, SslProtocols.Tls12, false);