NullReferenceException when using NetworkTransform with a RigidBody

Question

When I attempt to use NetworkServer.Spawn to create an object with a Rigidbody and a NetworkTransform set to Sync Rigidbody 3D, I get this:

NullReferenceException: Object reference not set to an instance of an object UnityEngine.Networking.NetworkTransform.SerializeMode3D (UnityEngine.Networking.NetworkWriter writer) (at C:/buildslave/unity/build/Extensions/Networking/Runtime/NetworkTransform.cs:251)

Answer 1

I was calling NetworkServer.Spawn in the Awake of another component before the NetworkTransform component had awoken. Since OnSerialize happens as soon as you call spawn, it was trying to pull data from an uninitialized reference to the Rigidbody.

UNET is now open source, and the code for NetworkTransform can be found here. Was useful for debugging this!