Resolved "Object reference not set to an instance of an object" when using raycast

"NullReferenceException: Object reference not set to an instance of an object
PlayerMove.Update () (at Assets/PlayerScripts/PlayerMove.cs:85)"

Yes, that should be easy to figure out right?

I am trying to fire a raycast with a mouse click. Upon clicking the designated key, I get the above error. I get the same error if there is no "if" statement. The main camera is a grandchild of the "Player" which this script is a component of. It goes Player > Cam Axis > Main Camera. Here is the relevant section of script. I'm sure it's something stupid but I don't even know where to start on this one.

Code (CSharp):

1.     public CharacterController controller;
2.     private Animator Anim;
3.     Camera cam; //<<<THIS IS RELATED TO THE LINE WITH THE ERROR
4.  
5.  
6.  
7.     private void Start()
8.     {
9.         controller = GetComponent<CharacterController>();
10.         Anim = GetComponentInChildren<Animator>();
11.         cam = Camera.main;  //<<<THIS IS RELATED TO THE LINE WITH THE ERROR
12.  
13.  
14.     }
15.  
16.     private void Update()
17.     {   //transform.LookAt(target);
18.  
19.               moveDirection = new Vector3 (0, 0, moveSpeed);
20.      //moveDirection = moving along 0x, 0y, (1, 0 or -1f)z
21.      moveDirection = transform.TransformDirection(moveDirection);
22.  
23.         if(!Input.GetKey(KeyCode.Mouse0) && !Input.GetKey(KeyCode.Mouse0))
24.         {
25.             CameraNone();
26.             Idle();
27.         }
28.         if(Input.GetKey(KeyCode.Mouse0) && !Input.GetKey(KeyCode.Mouse1))
29.         {
30.             CameraRot();
31.         }
32.         if(!Input.GetKey(KeyCode.Mouse0) && Input.GetKey(KeyCode.Mouse1))
33.         {
34.             PlayerRot();
35.         }
36.         else if(Input.GetKey(KeyCode.Mouse0) && Input.GetKey(KeyCode.Mouse1))
37.         {
38.             Move();
39.             //Debug.Log("000939030");
40.         }
41.         if(moveDirection == Vector3.zero && Input.GetKey(KeyCode.Mouse1)) //<<<THE ERROR ARISES WITHIN THIS STATEMENT
42.         {
43.             Debug.Log("Mouseclick");
44.             Ray ray = cam.ScreenPointToRay(Input.mousePosition);  //<<THIS IS THE LINE THROWING THE ERROR, LINE 85
45.             RaycastHit hit;
46.  
47.             if(Physics.Raycast(ray, out hit))
48.             {
49.                 Debug.Log("Raycast hit");
50.             }
51.  
52.         }
53.  
54.  
55.     }

 

This is a essentially a null ref error.

1. Find out what is null
2. Find out why it's null.
3. Fix it.

So, the error says line 85, which you point out is line 44. At first glance, I feel like cam is null. But, you should add a debug right before line 44 to print out the value of cam.

If it's null, then in Start, you are trying to assign the value to Camera.main.
Camera.main will return the camera that is assigned the MainCamera tag. So, make sure you have a camera that has that tag.

If it's not null, then you need to add some debug calls and see what is null in that line.

 

Yep, get on it now. Nobody here can help.

The answer is always the same... ALWAYS!

How to fix a NullReferenceException error

https://forum.unity.com/threads/how-to-fix-a-nullreferenceexception-error.1230297/

Three steps to success:
- Identify what is null <-- any other action taken before this step is WASTED TIME
- Identify why it is null
- Fix that

 

Somehow my MainCamera got untagged lol.

Tagging my MainCamera as MainCamera fixed it.

 

It was the "relevant section of the script." I doubt you all would want to look through 400 lines of code when 3 lines are where the problem was occurring.

 

Actually, we usually don't mind seeing the entire code as long as code tags are used. Sometimes errors aren't where we think they are. Or, they can be caused by something else.