Need help with error: NullReferenceException: Object reference not set to an instance of an object

Unity Engine
1

im trying to make it to where zombie spawn at empty gameobjects but i keep getting the error:

NullReferenceException: Object reference not set to an instance of an object
zombieSpawn.OnTriggerEnter (UnityEngine.Collider other) (at Assets/scripts/zombieSpawn.js:17)

any help would be appreciated. Here is my code

var Zombie : Transform;
var ZombieSpawn1 : Transform;
var ZombieSpawn2 : Transform;
var ZombieSpawn3 : Transform;
var ZombieSpawn4 : Transform;
var ZombieSpawn5 : Transform;


public var ZombiesSpawned = 0;

function OnTriggerEnter (other : Collider) {
    if (other.tag == "Player")
    {
        if (ZombiesSpawned < 5)
            {
        Instantiate(Zombie, ZombieSpawn1.position, Quaternion.Identity);
        ZombiesSpawned += 1;

        }
    }
}
2

Have you dragged blank a transform reference into the ZombieSpawn1 field on the game object where this script resides? Have you supplied a Zombie prefab to spawn?

3

I don’t see any code where you setting zombie and zombiespawn1.
Just verify you have them set and it should clear the null ref error. Zombie normally needs to be a GameObject not just the Transform.
You can add public to them. To set the spawn locations via the inspector.

4

I changed

var Zombie : Transform;
to
var Zombie : GameObject;

im still get the error

5

i"ve done both

6 
public var Zombie : GameObject;
public var ZombieSpawn1 : Transform;
public var ZombieSpawn2 : Transform;
public var ZombieSpawn3 : Transform;
public var ZombieSpawn4 : Transform;
public var ZombieSpawn5 : Transform;
public var ZombiesSpawned = 0;
function OnTriggerEnter (other : Collider) {
    if (other.tag == "Player")
    {
        if (ZombiesSpawned < 5)
        {
            if(Zombie != null)
            {
                Instantiate(Zombie, ZombieSpawn1.position, Quaternion.Identity);
                ZombiesSpawned += 1;
            }else
            {
                Debug.Log("Zombie is null - set it via code or in unity");
            }
        }
    }
}
7

I ran your code and it didn’t say “Zombie is null - set it via code or in unity” in the console and got the same error
im using a prefab for the zombie and empty game objects for the spawn points if that helps

8

found the problem
it is that in Quaternion.Identity i spelled it with a capital I and its spelled with a lower case like so Quaternion.identity

9

that’s interesting. I would expect that to produce a null ref.
good job, you got it fixed

10

Yeah, that is odd. That shouldn’t be a null error. As far as I know, Quaternion doesn’t implement Identity, so you should have received a different error.