Why am I getting a "Object reference not set to an instance of an object"

Questions & Answers
1

I am working on a menu, using unity’s ui. I have an empty scene, with a Canvas, a Panel and an image (square box). There use to be a lot more but this is all I need to get the error.

Attached to the canvas I have the following script attached:

using UnityEngine;
using UnityEngine.UI;

public class CharacterInventory : MonoBehaviour {
	public Image Socket0;

	void Awake () 
	{
		Socket0.sprite = Resources.Load<Sprite>("Sprites/spr-Shield-red");
	}
}

The “box” is attached to the script in socket0. The “Red Shield” appears in the box as it should however I am getting :

NullReferenceException: Object
reference not set to an instance of an
object CharacterInventory.Start () (at
Assets/Scripts/CharacterInventory.cs:9)

Anyone have any ideas as to why? Over 800 lines of code boils down to 1 line. I have tried a bunch of things but I keep getting the error and I have no idea why!!

Can anyone tell me what is causing this error, and how to fix it.

Thanks in advance

Richard M.

2

This will happen if you don’t actually have something set in for the Object. So you’re calling the object to do something, but its not actually there. You need to set the reference in the inspector, which I don’t believe you’re actually doing.
So to get around this error, or at least have it stop throwing out the error, try doing this

     void Awake () 
     {
         if(Socket0 != null)
              Socket0.sprite = Resources.Load<Sprite>("Sprites/spr-Shield-red");

         else if(Socket0 == null)
              Debug.Log("Socket0 Not Found!");
     }

This wont actually pop in your Image, but it will stop throwing the error, and it will let you know that your image isn’t there.