Could not create an instance of type X. Type is an interface or abstract class and cannot be instantiated.

[benjamin-achouche]

Could not create an instance of type X. Type is an interface or abstract class and cannot be instantiated.

[elgonzo]

The error is because all the deserializer knows is that the deserialization target type for some json object(s) is the interface IEpisodeSaveData which obviously is not type that can be instantiated. The deserializer also doesn't start reading the tea-leaves, trying to guess what you expect it to do with this dictionary having IEpisodeSaveData as its value type. So, it basically says "Nope. I have no clue what you want. No soup for you."

Your best way forward is probably to let the serializer put type metadata into the serialized json data, so the deserializer will know from this metadata which types to create. To do this, you will not only have to use TypeNameHandling = TypeNameHandling.Auto for the deserializer, but you will also have to use it for the serializer.

(the issue lies solely in the "eventFlags" prop)

No, it doesn't. It lies chiefly with the Dictionary<Character, IEpisodeSaveData> episodes dictionary. Note that once the deserializer would know which concrete IEpisodeSaveData type to use for a given json object, it would automatically also know the concrete Dictionary<T, bool> eventFlags type, because the concrete type for T is part of the type definition of the concrete IEpisodeSaveData classes. :-)

[benjamin-achouche]

Yeah that seemed to have fixed it ! Thanks !