Unable to use HttpClient from UDF, but static method is able to perform request in Console Application

[Connor Keevill]

Hi Govert, 

I've having a weird problem where I'm able to run a function in a console application, but not the same function from Excel.

Here is the method I am trying to call.

If I call from an console application it correctly outputs my IP address (as it should), however calling the corresponding UDF in Excel causes the following error: 

An error has occured: 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 ---

   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()

   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()

   at SignalAddIn.SignalConfigTestUtils.<SigTestServerConnection>d__1.MoveNext()

Any ideas what could be going wrong here? Guessing it's something related to the async nature of the method, but I don't know what.

Thanks for any help, 

Connor

[Govert van Drimmelen]

Hi Connor 

I wonder whether this is the same issue you have:  TLS1.2, Excel and .NET (google.com)

-Govert

[Bart Duijndam]

Hi all,

I just posted this in a different conversation. I believe I had a similar issue. It was solved by adding one line to AutOpen()

            // the next line is essential to prevent file-open errors.
            ServicePointManager.SecurityProtocol |= SecurityProtocolType.Tls12;

see: https://stackoverflow.com/questions/2859790/the-request-was-aborted-could-not-create-ssl-tls-secure-channel

Maybe this is of use.

Cheers,

Bart