Recently I wrote an article about getting all prediction scores from your ML.NET model. So, when we want to do this for an ONNX model we have loaded with ML.NET, that should work the same, right? Not really. Depending on the version of ML.NET, the data types of the downloaded Azure Custom Vision ONNX model are very hard to map on the .NET data types we use. In this article I will show how we can get the labels and scores from an ONNX model prediction in C#.

When trying to have an application work with an ONNX model I downloaded from the Microsoft Custom Vision portal, I got the following exception: TypeInitializationException: EntryPointNotFoundException: Unable to find an entry point named 'OrtGetApiBase' in DLL 'onnxruntime'. Searching for the error online did not yield any solutions. After solving the problem, I wanted to share the solution for anyone else running into the same exception.