空のプロジェクトでもこのエラーが発生しています。
Unity 5.4.03 を使用しています
UNetWeaver error: ResolveMethod failed NetworkBehaviour::SendTargetRPCInternal UnityEngine.Networking.NetworkBehaviour
UnityEngine.Debug:LogError(Object)
Unity.UNetWeaver.Log:Error(String) (at /Users/builduser/buildslave/unity/build/Extensions/Networking/Weaver/Program.cs:20)
Unity.UNetWeaver.Weaver:ResolveMethod(TypeReference, String) (at /Users/builduser/buildslave/unity/build/Extensions/Networking/Weaver/UNetWeaver.cs:1088)
Unity.UNetWeaver.Weaver:SetupTargetTypes() (at /Users/builduser/buildslave/unity/build/Extensions/Networking/Weaver/UNetWeaver.cs:1352)
Unity.UNetWeaver.Weaver:Weave(String, IEnumerable`1, IAssemblyResolver, String, String, String) (at /Users/builduser/buildslave/unity/build/Extensions/Networking/Weaver/UNetWeaver.cs:1652)
Unity.UNetWeaver.Weaver:WeaveAssemblies(IEnumerable`1, IEnumerable`1, IAssemblyResolver, String, String, String) (at /Users/builduser/buildslave/unity/build/Extensions/Networking/Weaver/UNetWeaver.cs:1763)
Unity.UNetWeaver.Program:Process(String, String, String, String[], String[], IAssemblyResolver, Action`1, Action`1) (at /Users/builduser/buildslave/unity/build/Extensions/Networking/Weaver/Program.cs:34)
UnityEditor.Scripting.Serialization.Weaver:WeaveUnetFromEditor(String, String, String, String, Boolean)