Connection was Forcibly Closed with Catalina API
If you are connecting to one of Catalina’s API endpoints (either REST or SOAP) and you are using https://, if you get an error saying the “Connection was Forcibly Closed,” this is normally because the web server requires a specific TLS version and your client isn’t using that.
If you are writing this in .NET, this can be easily overcome by adding this statement before you make a call to our API (it is normally fine to put it in the constructor or in some startup routine):
System.Net.ServicePointManager.SecurityProtocol =
System.Net.SecurityProtocolType.Tls12
| System.Net.SecurityProtocolType.Tls11
| System.Net.SecurityProtocolType.Tls
| System.Net.SecurityProtocolType.Ssl3;