SerializationException Type “is not marked as serializable” - But it is

Question

In Windows Forms, .NET Framework 4.0, I am trying to Serialize an instance of a class I wrote.

The class is marked as Serializable, but the form that uses the class

Answer 1

This is something you can run into with any JSON serialization, including Web API in MVC 4.

I found this post to be very helpful when I was getting a serialization except on a const int value. Any const value needs to be marked with the same attribute as in Nick Freeman's answer:

[field: NonSerializedAttribute]
const int iCantBeSerialized = 1;