So, while playing around with the Unity build, I've noticed an error (InvalidOperationException: This unpacker is located in the tail.) while decoding a valid MsgPack payload (at least I believe it's valid).

Here's the hex representation of a valid message: 82A17481A17404A46461746180

{ "t": { "t": 4 }, "data": {} } 

Pretty sure this is a valid message, both according to http://msgpack-json-editor.com/, the Python MsgPack implementation and going over it using the MsgPack spec.

A snippet to reproduce:

public static byte[] StringToByteArray(string hex) { return Enumerable.Range(0, hex.Length) .Where(x => x % 2 == 0) .Select(x => Convert.ToByte(hex.Substring(x, 2), 16)) .ToArray(); } MessagePackSerializer.Get<Dictionary<string, MessagePackObject> ().UnpackSingleObject(StringToByteArray("82A17481A17404A46461746180"));