DisconnectEvent error=6

Hi,

I am using HLAPI and testing some interpolation technique in a NetworkBehaviour. I have a host (NetworkClient+NetworkServer) that spawns a prefab on another client when it connects and it sends state updates. At some point, the client disconnects from the host, the prefab disappears and I get this error:
Client event: host=0 event=DisconnectEvent error=6
UnityEngine.Networking.NetworkIdentity:UNetStaticUpdate()

What is error 6?

Thanks.