Dynamics 365 Plugin call External REST API - SSL/TSL could not create channel issue - plugins

Question

I have a task to call the external REST API to get data from third party application.
In that, i have created a C# Console application for tried this and it is working fine and i can get the data from thirty party application via REST API.
The same code used to tried in Dynamics Custom workflow\Plugin, i have got a error below. Please give your valuable suggestion on this.
"System.Net.WebException: The request was aborted: Could not create SSL/TLS secure channel."
Note: The below options are tried but no luck.
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12;
ServicePointManager.ServerCertificateValidationCallback += new RemoteCertificateValidationCallback(AlwaysGoodCertificate);
ServicePointManager.Expect100Continue = true;
Thanks,
Vasanth

Answer 1

It is not clear how you are calling external API from D365 Plugin.
// Call external API
static async Task<bool> CallExternalAPI(Guid beziehungId)
{
bool status = false;
HttpClient apiClient = new HttpClient();
apiClient.DefaultRequestHeaders.Accept.Clear();
apiClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
string url = #"https://reqres.in/api/users?page=2";
HttpResponseMessage response = await apiClient.GetAsync(url);
if (response.IsSuccessStatusCode)
{
var result = response.Content.ReadAsStringAsync().GetAwaiter().GetResult();
}
return status;
}
If your problem with SSL/TLS secure channel you can use WebClient.
// Could not create SSL/TLS secure channel.
// Use (SecurityProtocolType)3072
using (WebClient client = new WebClient())
{
client.Headers.Add(HttpRequestHeader.UserAgent, "AvoidError");
ServicePointManager.Expect100Continue = true;
//ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072;
htmlCode = client.DownloadString("MY LINK");
//passing the URL again to function from which to extract the content and compare from above content.
strNewCompanyCode = client.DownloadString("MY LINK");
}