What does this error mean?

Hello, Im getting this error form around 2 days after updating to Unity 5.6
I dont know what this means :confused: , anyone could please help me with this?
Error :-
“GameObject X is a prefab, it can’t be spawned. This will cause errors in builds.UnityEngine.Networking.NetworkIdentity:UNetStaticUpdate()”
Where “X” is my player prefab name

And also i get this error :- “spawn scene object not found for 1” when i try to connect to an existing server and it doesnt spawn

Try simply resetting the NetworkIdentity component, that worked for me.