When I install VTSCADA 12.1.12 and try to load the WeatherApp sample application available on your website I receive an error: "HTTP server error Unknown Error -10013"

I progress past this error and attempt to configure the DemoSystem to allow connections from the DSN I created using the VTSCADA ODBC driver. The local DSN fails to connect to the server.

What is the cause of this error and how can I get my DSN to connect?

Sorry about that, that sample app is quite old. It uses the JSON/XML driver with a custom expression. If you head to https://openweathermap.org/current and get yourself a free API key, you can enter the basic url for your location in the existing JSON/XML driver tag and the data should come to life.