NullReferenceException: Object reference not set to an instance of an object

Unity Engine
1

Hi, so, I have been trying to make my first 3D game and I’ve been attempting to make a character controller and I’ve seen a couple other threads however they don’t solve my problem

using System.Collections;
using UnityEngine;

public class Movement : MonoBehaviour
{
    Rigidbody rb;
    [SerializeField] float MovementSpeed = 5f;
    [SerializeField] float JumpHeight = 5f;
    // Start is called before the first frame update
    void Start()
    {
       
    }

    // Update is called once per frame
    void FixedUpdate()
    {
        //Movement
        if (Input.GetKey(KeyCode.W))
        {
            //Next line has a bug
            rb.AddForce(transform.forward * MovementSpeed);
        }
        if (Input.GetKey(KeyCode.S))
        {
            //Next line has a bug
            rb.AddForce(-transform.forward * MovementSpeed);
        }
        if (Input.GetKey(KeyCode.A))
        {
            //Next line has a bug
            rb.AddForce(-transform.right * MovementSpeed);
        }
        if (Input.GetKey(KeyCode.D))
        {
            //Next line has a bug
            rb.AddForce(transform.right * MovementSpeed);
        }
    }
}

So yeah, and help is appreciated! I’ve been trying to fix this but I don’t see what’s wrong, or as I’m new to this c# thingy it’s a dumb question

(Also, I have a RigidBody in the GameObject that this script is in)

2

And no I’m not gonna use the built-in Character Controller script, it’s too complex

3

How to fix a NullReferenceException error

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

Steps to success:

  • Identify what is null
  • Identify why it is null
  • Fix that
4

You will meet nullreference error plenty of times, so you should really check what Kurt Dekker provided. But if you want quick answer…
You always need to write it like that:

Rigidbody2D rb;
void Start()
{
   rb = GetComponent<Rigidbody2D>();
}

Just to get component that you wrote, because compiler doesn’t know which object’s is Rigidbody. By writing rb = GetComponent(), you basically saying that “rb” equals to rigidbody2d component, that is attached to a “movement” script’s gameobject.
But you can also drag and drop RB component in inspector.
[SerializeField] private Rigidbody2D rb;
With that, you won’t need to write GetComponent in script, but you need to make sure that you dragged and dropped Rigidbody2D component in inspector. [SerializeField] basically serializes private field, so you can see it in ispector, but you can also make it public RigidBody rb, and it will do same thing.

5

I don’t even know how to respond to that allegation, but sure, I’ll take it at face value. /shrug

If you just want a functioning FPS controller, here’s one based on CC:

https://discussions.unity.com/t/855344

It supports run, walk, jump, slide, crouch… it’s crazy-nutty!!

6

I know what Serialize field is, I’ve literally used it in my script! Thanks for your help anyway!

7

Sorry but I want to make it from scratch, it’s a bit more fun and there’s learning along the way too!

8

What line is the error on? Please post the exact error message.

9

Rather than pushing back on that comment, maybe you would like to absorb the first part of the reply which is the solution to your problem. You didn’t provide the line the error was on yet someone gave you the solution so kudos to them!

1 Like