NullReferenceException help

Unity Engine
1

hi can someone please help me with error, I have tried youtube and google but i just don’t understand what I need to do. also, I need this done soon as I am making the game as a gift for a friend.

NullReferenceException: Object reference not set to an instance of an object
Player.Damage () (at Assets/Scripts/Player.cs:109)
Enemy.OnTriggerEnter2D (UnityEngine.Collider2D other) (at Assets/Scripts/Enemy.cs:38)

and here is the script

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Player : MonoBehaviour
{
    [SerializeField]
    private float _speed = 3.5f;
    private float _speedMultiplier = 2;
    [SerializeField]
    private GameObject _LazerPrefab;
    [SerializeField]
    private GameObject _TripleShotPrefab;
    [SerializeField]
    private float _fireRate = 0.5f;
    private float _canFire = 1f;
    [SerializeField]
    private int _lives = 3;
    private SpawnManager _spawnManager;
    [SerializeField]
    private bool _isTripleShotActive = false;
    [SerializeField]
    private bool _isSpeedBoostActive = false;
    private bool _isShieldsActive = false;
    [SerializeField]
    private GameObject _shieldVisualizer;
    private UIManager _uiManager;
   

   
 





    // Start is called before the first frame update
    void Start()
    {

        transform.position = new Vector3(0, 0, 0);
        _spawnManager = GameObject.Find("Spawn_Manager").GetComponent<SpawnManager>();

        if (_spawnManager == null)
        {

        }
    }

    // Update is called once per frame
    void Update()
    {
        CalculateMovement();

        if (Input.GetKeyDown(KeyCode.Space) && Time.time > _canFire)
        {
            FireLazer();
        }

    }

    void CalculateMovement()
    {
        float horizontalInput = Input.GetAxis("Horizontal");
        float VerticalInput = Input.GetAxis("Vertical");
        Vector3 direction = new Vector3(horizontalInput, VerticalInput, 0);
        transform.Translate(direction * _speed * Time.deltaTime);





        transform.position = new Vector3(transform.position.x, Mathf.Clamp(transform.position.y, -3.8f, 0), 0);

        if (transform.position.x > 11.3f)
        {
            transform.position = new Vector3(-11.3f, transform.position.y, 0);
        }
        else if (transform.position.x < -11.3f)
        {
            transform.position = new Vector3(11.3f, transform.position.y, 0);
        }
    }


    void FireLazer()
    {
        _canFire = Time.time + _fireRate;

        if (_isTripleShotActive == true)
        {
            Instantiate(_TripleShotPrefab, transform.position, Quaternion.identity);
        }
        else
            Instantiate(_LazerPrefab, transform.position + new Vector3(0, 1.05f, 0), Quaternion.identity);
    }

    public void Damage()
    {
        if (_isShieldsActive == true)
        {
            _isShieldsActive = false;
            _shieldVisualizer.SetActive(false);
            return;
        }

        _lives --;

        _uiManager.UpdateLives(_lives);

        if (_lives < 1)
        {
            _spawnManager.OnPlayerDeath();
            Destroy(this.gameObject);
        }
    }

    public void TripleShotActive()
    {
        _isTripleShotActive = true;
        StartCoroutine(TripleShotPowerDownRoutine());
    }
    IEnumerator TripleShotPowerDownRoutine()
    {
        yield return new WaitForSeconds(5.0f);
        _isTripleShotActive = false;
    }

    public void SpeedBoostActive()
    {
        _isSpeedBoostActive = true;
        _speed *= _speedMultiplier;
        StartCoroutine(SpeedBoostPowerDownRoutine());
    }

    IEnumerator SpeedBoostPowerDownRoutine()
    {
        yield return new WaitForSeconds(5.0f);
        _isSpeedBoostActive = false;
        _speed /= _speedMultiplier;
    }
    public void ShieldActive()
    {
        _isShieldsActive = true;
        _shieldVisualizer.SetActive(true);
    }

   
}

but if you can, can you explain clearly because I have learn disabilities so I find it hard to understand

2

You haven’t set your _uiManager reference.

3

thank you so much mate