The request was aborted: Could not create SSL/TLS secure channel.

Question

Hi All,

This Application is based on .NET framework 4.5 and application works fine, but it has a function that calls external API for SMS gateway, that's where this error is coming.
I have followed all answers for this question, but no luck.

This application is hosted on Windows Server 2012 R2, and it is TLS 1.2 enabled by default.
I also double check whether it's Application problem or Server itself by calling the SMS GW API thourhg postman inside Serever and it works fine.

My problem is eventhough i rebuild the Application with .NET target framework to 4.7 still this error comes whenever application calling SMS GW API.

full error message

System.Net.Http.HttpRequestException: An error occurred while sending the request. ---> System.Net.WebException: The request was aborted: Could not create SSL/TLS secure channel.  
   at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)  
   at System.Net.Http.HttpClientHandler.GetResponseCallback(IAsyncResult ar)  
   --- End of inner exception stack trace ---  

Answer 1

Hi. Thank you for your question and reaching out.

You must start by include this:

// using System.Net;
ServicePointManager.Expect100Continue = true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
// Use SecurityProtocolType.Ssl3 if needed for compatibility reasons

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