The underlying connection was closed: An unexpected error occurred on a send.

[pgayakwad]

Hello,

I have integrated Authorize.net payment gateway in SharePoint 2013 On-premises. I am using Authorize.net dll and it was running fine on production till Sep 25, 2020. But now, we are getting error as "The underlying connection was closed: An unexpected error occurred on a send.".

I have already implemented below:

System.Net.ServicePointManager.Expect100Continue = true;
System.Net.ServicePointManager.SecurityProtocol = System.Net.SecurityProtocolType.Tls12;

Please help us if there is any further solution available to the fixes.

Thanks