Unity 4 to 5 mesh rotate problem

When I tried Updating my project from the last version of unity 4 to unity 5 I picked up the following error and I am not understanding it.

Cooking::cookConvexMesh: user-provided hull must have less than 256 vertices!
UnityEngine.Transform:Rotate(Single, Single, Single)
PlanetRotate:Update() (at Assets/Scripts/PlanetRotate.cs:15)

The script it brings up when I click on it is the following.

using UnityEngine;
using System.Collections;

public class PlanetRotate : MonoBehaviour {
public float rotationSpeed = 5.0f;//Speed of rotation.
	
	void Update() 
	{
    	transform.Rotate(0,0,rotationSpeed*Time.deltaTime);//Causes rotation,
	}
}

All that script does is make my planets rotate.

That’s not where your problem is. It means you have a convex mesh collider somewhere with more than 256 vertices (which is a really tiny number, so pretty much every convex mesh collider is going to have this problem). Unity upgraded the underlying PhysX package with unity 5. I can’t find the bug report, but Unity is aware of the situation. Not sure what the timeline is.

Note: even the stock sphere mesh that comes with unity has more than 256 verts, so you can’t use it for a convex mesh collider. Use a sphere collider instead.