I keep getting this error in Unity

Questions & Answers
1

Hello! I’m trying to make a Roll a ball game, however I keep getting this:

NullReferenceException: Object reference not set to an instance of an object
PlayerController.FixedUpdate () (at Assets/Scripts/PlayerController.cs:47)

NullReferenceException: Object reference not set to an instance of an object
PlayerController.OnCollisionEnter () (at Assets/Scripts/PlayerController.cs:53)

using UnityEngine;
using System.Collections;

public class PlayerController : MonoBehaviour
{

    private Rigidbody rb;
    public float speed;
    public float jumpheight;
    int JumpCount = 0;
    public int MaxJumps = 1;
    public AudioSource source;
    public AudioClip jumpsound;
    public AudioClip hitsound;

    void Start()
    {
        JumpCount = MaxJumps;
        source = gameObject.GetComponent<AudioSource>();
    }

    public void Jump()
    {
        rb.AddForce(new Vector3(0, jumpheight, 0), ForceMode.Impulse);
        source.clip = jumpsound;
        source.Play();
    }

    void Update()
    {
        rb = GetComponent<Rigidbody>();
        if (Input.GetKeyDown("space"))
        {
            if (JumpCount > 0)
            {
                Jump();
                JumpCount -= 1;
            }
        }
    }

    void FixedUpdate()
    {
        float moveHorizontal = Input.GetAxis("Horizontal");
        float moveVertical = Input.GetAxis("Vertical");
        Vector3 movement = new Vector3(moveHorizontal, 0.0f, moveVertical);
        rb.AddForce(movement * speed);

    }

    void OnCollisionEnter()
    {
        rb.velocity = Vector3.zero;
        JumpCount = MaxJumps;
        source.clip = hitsound;
        source.Play();
    }
}

It doesn’t affect the gameplay, but it’s there. Why?

Rand 47: rb.AddForce(movement * speed);
Rand 53: rb.velocity = Vector3.zero;

2

That is because the variable rb is not assigned yet when you call it in FixedUpdate, FixedUpdate is called before Update, and also there is no need to assign the variable rb
in Update.
Please move rb = GetComponent(); to the Start function, just like the **source ** variable in your code.