[Part 5] SceneTransition null reference error

[Bachok]

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Hi! I’m facing a NullReferenceException error in my Unity project, and I’m not sure how to resolve it. The error message is:

NullReferenceException: Object reference not set to an instance of an object
SceneTransition.Awake() (at Assets/code/SceneTransition.cs:27)

in short, I wrote code for sceneFader and everything worked perfectly, but after I added the lighting to the scene, everything stopped working and started giving this error.

Here is video :

https://i.imgur.com/Ow2POcI.mp4

Here is my code from SceneTransition:

<code>using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;

public class SceneTransition : MonoBehaviour
{
    // Start is called before the first frame update

    [SerializeField] private string transitionTo;

    [SerializeField] private Transform startPoint;

    [SerializeField] private Vector2 exitDirection;

    [SerializeField] private float exitTime;

    private void Awake()
    {
        if (GameManager.Instance.transitionedFromScene == transitionTo)
        {
            PlayerController.Instance.transform.position = startPoint.position;

            StartCoroutine(PlayerController.Instance.WalkIntoNewScene(exitDirection, exitTime));
        }

        StartCoroutine(UIManager.Instance.sceneFader.Fade(SceneFader.FadeDirection.Out));
    }

    private void OnTriggerEnter2D(Collider2D _other)
    {
        if (_other.CompareTag("Player"))
        {
            GameManager.Instance.transitionedFromScene = SceneManager.GetActiveScene().name;

            PlayerController.Instance.pState.cutscene = true;

            StartCoroutine(UIManager.Instance.sceneFader.FadeAndLoadScene(SceneFader.FadeDirection.In, transitionTo));
        }
    }
}</code>

Here is code of UIManager:

<code>using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class UIManager : MonoBehaviour
{
    public SceneFader sceneFader;

    public static UIManager Instance;
    private void Awake()
    {
        if (Instance != null && Instance != this)
        {
            Destroy(gameObject);
        }
        else
        {
            Instance = this;
        }
        DontDestroyOnLoad(gameObject);

        sceneFader = GetComponentInChildren<SceneFader>();
    }
}
</code>

Here is code of GameManager:

<code>using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class GameManager : MonoBehaviour
{
    public string transitionedFromScene;

    public static GameManager Instance { get; private set; }
    private void Awake()
    {
        if (Instance != null && Instance != this)
        {
            Destroy(gameObject);
        }
        else
        {
            Instance = this;
        }
        DontDestroyOnLoad(gameObject);
    }
}
</code>

Here is code of SceneFader:

<code>using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.SceneManagement;

public class SceneFader : MonoBehaviour
{
    [SerializeField] private float fadeTime;

    private Image fadeOutUIImage;

    public enum FadeDirection
    {
        In,
        Out
    }

    // Start is called before the first frame update
    void Start()
    {
        fadeOutUIImage = GetComponent<Image>();
    }

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

    }

    public IEnumerator Fade(FadeDirection _fadeDirection)
    {
        float _alpha = _fadeDirection == FadeDirection.Out ? 1 : 0;
        float _fadeEndValue = _fadeDirection == FadeDirection.Out ? 0 : 1;

        if (_fadeDirection == FadeDirection.Out)
        {
            while (_alpha >= _fadeEndValue)
            {
                SetColorImage(ref _alpha, _fadeDirection);

                yield return null;
            }

            fadeOutUIImage.enabled = false;
        }
        else
        {
            fadeOutUIImage.enabled = true;

            while (_alpha <= _fadeEndValue)
            {
                SetColorImage(ref _alpha, _fadeDirection);

                yield return null;
            }
        }
    }

    public IEnumerator FadeAndLoadScene(FadeDirection _fadeDirection, string _sceneToLoad)
    {
        fadeOutUIImage.enabled = true;

        yield return Fade(_fadeDirection);

        SceneManager.LoadScene(_sceneToLoad);
    }

    void SetColorImage(ref float _alpha, FadeDirection _fadeDirection)
    {
        fadeOutUIImage.color = new Color(fadeOutUIImage.color.r, fadeOutUIImage.color.g, fadeOutUIImage.color.b, _alpha);

        _alpha += Time.deltaTime * (1 / fadeTime) * (_fadeDirection == FadeDirection.Out ? -1 : 1);
    }
}</code>

Here is code of PlayerStateList:

<code>using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PlayerStateList : MonoBehaviour
{
    public bool jumping = false;
    public bool dashing = false;
    public bool recoilingX, recoilingY;
    public bool lookingRight;
    public bool invincible;
    public bool healing;
    public bool casting;
    public bool cutscene = false;
}
</code>

And Here is code of PlayerController:

<code>using System.Collections;
using System.Collections.Generic;
using System.Net.Sockets;
using UnityEngine;
using UnityEngine.UIElements;
using UnityEngine.UI;

public class PlayerController : MonoBehaviour
{
    [Header("Horizontal Movement Settings:")]
    [SerializeField] private float walkSpeed = 1; //sets the players movement speed on the ground
    [Space(5)]

    [Header("Vertical Movement Settings")]
    [SerializeField] private float jumpForce = 45f; //sets how hight the player can jump

    private int jumpBufferCounter = 0; //stores the jump button input
    [SerializeField] private int jumpBufferFrames; //sets the max amount of frames the jump buffer input is stored

    private float coyoteTimeCounter = 0; //stores the Grounded() bool
    [SerializeField] private float coyoteTime; ////sets the max amount of frames the Grounded() bool is stored

    private int airJumpCounter = 0; //keeps track of how many times the player has jumped in the air
    [SerializeField] private int maxAirJumps; //the max no. of air jumps

    private float gravity; //stores the gravity scale at start
    [Space(5)]

    [Header("Ground Check Settings:")]
    [SerializeField] private Transform groundCheckPoint; //point at which ground check happens
    [SerializeField] private float groundCheckY = 0.2f; //how far down from ground chekc point is Grounded() checked
    [SerializeField] private float groundCheckX = 0.5f; //how far horizontally from ground chekc point to the edge of the player is
    [SerializeField] private LayerMask whatIsGround; //sets the ground layer
    [Space(5)]

    [Header("Dash Settings")]
    [SerializeField] private float dashSpeed; //speed of the dash
    [SerializeField] private float dashTime; //amount of time spent dashing
    [SerializeField] private float dashCooldown; //amount of time between dashes
    [SerializeField] GameObject dashEffect;
    private bool canDash = true, dashed;
    [Space(5)]

    [Header("Attack Settings:")]
    [SerializeField] private Transform SideAttackTransform; //the middle of the side attack area
    [SerializeField] private Vector2 SideAttackArea; //how large the area of side attack is

    [SerializeField] private Transform UpAttackTransform; //the middle of the up attack area
    [SerializeField] private Vector2 UpAttackArea; //how large the area of side attack is

    [SerializeField] private Transform DownAttackTransform; //the middle of the down attack area
    [SerializeField] private Vector2 DownAttackArea; //how large the area of down attack is

    [SerializeField] private LayerMask attackableLayer; //the layer the player can attack and recoil off of

    private float timeBetweenAttack, timeSinceAttck;

    [SerializeField] private float damage; //the damage the player does to an enemy

    [SerializeField] private GameObject slashEffect; //the effect of the slashs

    bool restoreTime;
    float restoreTimeSpeed;
    [Space(5)]

    [Header("Recoil Settings:")]
    [SerializeField] private int recoilXSteps = 5; //how many FixedUpdates() the player recoils horizontally for
    [SerializeField] private int recoilYSteps = 5; //how many FixedUpdates() the player recoils vertically for

    [SerializeField] private float recoilXSpeed = 100; //the speed of horizontal recoil
    [SerializeField] private float recoilYSpeed = 100; //the speed of vertical recoil

    private int stepsXRecoiled, stepsYRecoiled; //the no. of steps recoiled horizontally and verticall
    [Space(5)]

    [Header("Health Settings")]
    public int health;
    public int maxHealth;
    [SerializeField] GameObject bloodSpurt;
    [SerializeField] float hitFlashSpeed;
    public delegate void OnHealthChangedDelegate();
    [HideInInspector] public OnHealthChangedDelegate onHealthChangedCallback;

    float healTimer;
    [SerializeField] float timeToHeal;
    [Space(5)]

    [Header("Mana Settings")]
    [SerializeField] UnityEngine.UI.Image manaStorage;

    [SerializeField] float mana;
    [SerializeField] float manaDrainSpeed;
    [SerializeField] float manaGain;
    [Space(5)]

    [Header("Spell Settings")]
    //spell stats
    [SerializeField] float manaSpellCost = 0.3f;
    [SerializeField] float timeBetweenCast = 0.5f;
    float timeSinceCast;
    [SerializeField] float spellDamage; //upspellexplosion and downspellfireball
    [SerializeField] float downSpellForce; // desolate dive only
    //spell cast objects
    [SerializeField] GameObject sideSpellFireball;
    [SerializeField] GameObject upSpellExplosion;
    [SerializeField] GameObject downSpellFireball;
    [Space(5)]

    [HideInInspector] public PlayerStateList pState;
    private Animator anim;
    private Rigidbody2D rb;
    private SpriteRenderer sr;

    //Input Variables
    private float xAxis, yAxis;
    private bool attack = false;

    public static PlayerController Instance;

    private void Awake()
    {
        if (Instance != null && Instance != this)
        {
            Destroy(gameObject);
        }
        else
        {
            Instance = this;
        }
        DontDestroyOnLoad(gameObject);
    }

    // Start is called before the first frame update
    void Start()
    {
        pState = GetComponent<PlayerStateList>();

        rb = GetComponent<Rigidbody2D>();
        sr = GetComponent<SpriteRenderer>();

        anim = GetComponent<Animator>();

        gravity = rb.gravityScale;

        Mana = mana;
        manaStorage.fillAmount = Mana;
    }

    private void OnDrawGizmos()
    {
        Gizmos.color = Color.red;
        Gizmos.DrawWireCube(SideAttackTransform.position, SideAttackArea);
        Gizmos.DrawWireCube(UpAttackTransform.position, UpAttackArea);
        Gizmos.DrawWireCube(DownAttackTransform.position, DownAttackArea);
    }

    // Update is called once per frame
    void Update()
    {
        if (pState.cutscene) return;

        GetInputs();
        UpdateJumpVariables();

        if (pState.dashing || pState.healing) return;
        Flip();
        Move();
        Jump();
        StartDash();
        Attack();
        RestoreTimeScale();
        FlashWhileInvincible();
        Heal();
        CastSpell();
    }
    private void OnTriggerEnter2D(Collider2D _other) //for up and down cast spell
    {
        if (_other.GetComponent<Enemy>() != null && pState.casting)
        {
            _other.GetComponent<Enemy>().EnemyHit(spellDamage, (_other.transform.position - transform.position).normalized, -recoilYSpeed);
        }
    }

    private void FixedUpdate()
    {
        if (pState.cutscene) return;
        if (pState.dashing) return;
        Recoil();
    }

    void GetInputs()
    {
        xAxis = Input.GetAxisRaw("Horizontal");
        yAxis = Input.GetAxisRaw("Vertical");
        attack = Input.GetButtonDown("Attack");
    }

    void Flip()
    {
        if (xAxis < 0)
        {
            transform.localScale = new Vector2(-3, transform.localScale.y);
            pState.lookingRight = false;
        }
        else if (xAxis > 0)
        {
            transform.localScale = new Vector2(3, transform.localScale.y);
            pState.lookingRight = true;
        }
    }

    private void Move()
    {
        rb.velocity = new Vector2(walkSpeed * xAxis, rb.velocity.y);
        anim.SetBool("Walking", rb.velocity.x != 0 && Grounded());
    }

    void StartDash()
    {
        if (Input.GetButtonDown("Dash") && canDash && !dashed)
        {
            StartCoroutine(Dash());
            dashed = true;
        }

        if (Grounded())
        {
            dashed = false;
        }
    }

    IEnumerator Dash()
    {
        canDash = false;
        pState.dashing = true;
        anim.SetTrigger("Dashing");
        rb.gravityScale = 0;
        int _dir = pState.lookingRight ? 1 : -1;
        rb.velocity = new Vector2(_dir * dashSpeed, 0);
        if (Grounded()) Instantiate(dashEffect, transform);
        if (!Grounded()) Instantiate(dashEffect, transform);
        yield return new WaitForSeconds(dashTime);
        rb.gravityScale = gravity;
        pState.dashing = false;
        yield return new WaitForSeconds(dashCooldown);
        canDash = true;
    }


    public IEnumerator WalkIntoNewScene(Vector2 _exitDir, float _delay)
    {
        if(_exitDir.y > 0)
        {
            rb.velocity = jumpForce * _exitDir;
        }
        if (_exitDir.x != 0)
        {
            xAxis = _exitDir.x > 0 ? 1: -1;
            Move();
        }
        Flip();
        yield return new WaitForSeconds(_delay);
        pState.cutscene = false;
    }


    void Attack()
    {
        timeSinceAttck += Time.deltaTime;
        if (attack && timeSinceAttck >= timeBetweenAttack)
        {
            timeSinceAttck = 0;
            anim.SetTrigger("Attacking");

            if (yAxis == 0 || yAxis < 0 && Grounded())
            {
                Hit(SideAttackTransform, SideAttackArea, ref pState.recoilingX, recoilXSpeed);
                Instantiate(slashEffect, SideAttackTransform);
            }
            else if (yAxis > 0)
            {
                Hit(UpAttackTransform, UpAttackArea, ref pState.recoilingY, recoilYSpeed);
                SlashEffectAtAngle(slashEffect, 80, UpAttackTransform);
            }
            else if (yAxis < 0 && !Grounded())
            {
                Hit(DownAttackTransform, DownAttackArea, ref pState.recoilingY, recoilYSpeed);
                SlashEffectAtAngle(slashEffect, -90, DownAttackTransform);
            }
        }

    }
    void Hit(Transform _attackTransform, Vector2 _attackArea, ref bool _recoilDir, float _recoilStrength)
    {
        Collider2D[] objectsToHit = Physics2D.OverlapBoxAll(_attackTransform.position, _attackArea, 0, attackableLayer);

        if (objectsToHit.Length > 0)
        {
            _recoilDir = true;
        }
        for (int i = 0; i < objectsToHit.Length; i++)
        {
            if (objectsToHit[i].GetComponent<Enemy>() != null)
            {
                objectsToHit[i].GetComponent<Enemy>().EnemyHit
                    (damage, (transform.position - objectsToHit[i].transform.position).normalized, _recoilStrength);
                    Mana += manaGain;

            }
        }
    }
    void SlashEffectAtAngle(GameObject _slashEffect, int _effectAngle, Transform _attackTransform)
    {
        _slashEffect = Instantiate(_slashEffect, _attackTransform);
        _slashEffect.transform.eulerAngles = new Vector3(0, 0, _effectAngle);
        _slashEffect.transform.localScale = new Vector2(transform.localScale.x / 3, transform.localScale.y / 3);
    }
    void Recoil()
    {
        if (pState.recoilingX)
        {
            if (pState.lookingRight)
            {
                rb.velocity = new Vector2(-recoilXSpeed, 0);
            }
            else
            {
                rb.velocity = new Vector2(recoilXSpeed, 0);
            }
        }

        if (pState.recoilingY)
        {
            rb.gravityScale = 0;
            if (yAxis < 0)
            {
                rb.velocity = new Vector2(rb.velocity.x, recoilYSpeed);
            }
            else
            {
                rb.velocity = new Vector2(rb.velocity.x, -recoilYSpeed);
            }
            airJumpCounter = 0;
        }
        else
        {
            rb.gravityScale = gravity;
        }

        //stop recoil
        if (pState.recoilingX && stepsXRecoiled < recoilXSteps)
        {
            stepsXRecoiled++;
        }
        else
        {
            StopRecoilX();
        }
        if (pState.recoilingY && stepsYRecoiled < recoilYSteps)
        {
            stepsYRecoiled++;
        }
        else
        {
            StopRecoilY();
        }

        if (Grounded())
        {
            StopRecoilY();
        }
    }
    void StopRecoilX()
    {
        stepsXRecoiled = 0;
        pState.recoilingX = false;
    }
    void StopRecoilY()
    {
        stepsYRecoiled = 0;
        pState.recoilingY = false;
    }
    public void TakeDamage(float _damage)
    {
        Health -= Mathf.RoundToInt(_damage);
        StartCoroutine(StopTakingDamage());
    }
    IEnumerator StopTakingDamage()
    {
        pState.invincible = true;
        GameObject _bloodSpurtParticles = Instantiate(bloodSpurt, transform.position, Quaternion.identity);
        Destroy(_bloodSpurtParticles, 1.5f);
        anim.SetTrigger("TakeDamage");
        yield return new WaitForSeconds(1f);
        pState.invincible = false;
    }
    void FlashWhileInvincible()
    {
        sr.material.color = pState.invincible ? Color.Lerp(Color.white, Color.black, Mathf.PingPong(Time.time * hitFlashSpeed, 1.0f)) : Color.white;
    }
    void RestoreTimeScale()
    {
        if (restoreTime)
        {
            if (Time.timeScale < 1)
            {
                Time.timeScale += Time.deltaTime * restoreTimeSpeed;
            }
            else
            {
                Time.timeScale = 1;
                restoreTime = false;
            }
        }
    }
    public void HitStopTime(float _newTimeScale, int _restoreSpeed, float _delay)
    {
        restoreTimeSpeed = _restoreSpeed;
        if (_delay > 0)
        {
            StopCoroutine(StartTimeAgain(_delay));
            StartCoroutine(StartTimeAgain(_delay));
        }
        else
        {
            restoreTime = true;
        }
        Time.timeScale = _newTimeScale;
    }
    IEnumerator StartTimeAgain(float _delay)
    {
        restoreTime = true;
        yield return new WaitForSeconds(_delay);
    }
    public int Health
    {
        get { return health; }
        set
        {
            if (health != value)
            {
                health = Mathf.Clamp(value, 0, maxHealth);

                if (onHealthChangedCallback != null)
                {
                    onHealthChangedCallback.Invoke();
                }
            }
        }
    }
    void Heal()
    {
        if (Input.GetButton("Healing") && Health < maxHealth && Mana > 0 && !pState.jumping && !pState.dashing)
        {
            pState.healing = true;
            anim.SetBool("Healing", true);

            //healing
            healTimer += Time.deltaTime;
            if (healTimer >= timeToHeal)
            {
                Health++;
                healTimer = 0;
            }

            //drain mana
            Mana -= Time.deltaTime * manaDrainSpeed;
        }
        else
        {
            pState.healing = false;
            anim.SetBool("Healing", false);
            healTimer = 0;
        }
    }
    float Mana
    {
        get { return mana; }
        set
        {
            //if mana stats change
            if (mana != value)
            {
                mana = Mathf.Clamp(value, 0, 1);
                manaStorage.fillAmount = Mana;
            }
        }
    }

    void CastSpell()
    {
        if (Input.GetButtonDown("CastSpell") && timeSinceCast >= timeBetweenCast && Mana >= manaSpellCost)
        {
            pState.casting = true;
            timeSinceCast = 0;
            StartCoroutine(CastCoroutine());
        }
        else
        {
            timeSinceCast += Time.deltaTime;
        }

        if (Grounded())
        {
            //disable downspell if on the ground

            downSpellFireball.SetActive(false);
        }
        //if down spell is active, force player down until grounded
        if (downSpellFireball.activeInHierarchy)
        {
            rb.velocity += downSpellForce * Vector2.down;
        }

    }

    IEnumerator CastCoroutine()
    {
        anim.SetBool("Casting", true);
        yield return new WaitForSeconds(0.15f);

        //side cast
        if (yAxis == 0 || (yAxis < 0 && Grounded()))
        {
            GameObject _fireBall = Instantiate(sideSpellFireball, SideAttackTransform.position, Quaternion.identity);

            //flip fireball
            if (pState.lookingRight)
            {
                _fireBall.transform.eulerAngles = Vector3.zero; // if facing right, fireball continues as per normal
            }
            else
            {
                _fireBall.transform.eulerAngles = new Vector2(_fireBall.transform.eulerAngles.x, 180);
                //if not facing right, rotate the fireball 180 deg
            }
            pState.recoilingX = true;
        }

        //up cast
        else if (yAxis > 0)
        {
            Instantiate(upSpellExplosion, transform);
            rb.velocity = Vector2.zero;
        }

        //down cast
        else if (yAxis < 0 && !Grounded())
        {
            downSpellFireball.SetActive(true);
        }

        Mana -= manaSpellCost;
        anim.SetBool("Casting", false);
        pState.casting = false;
    }

    public bool Grounded()
    {
        if (Physics2D.Raycast(groundCheckPoint.position, Vector2.down, groundCheckY, whatIsGround)
            || Physics2D.Raycast(groundCheckPoint.position + new Vector3(groundCheckX, 0, 0), Vector2.down, groundCheckY, whatIsGround)
            || Physics2D.Raycast(groundCheckPoint.position + new Vector3(-groundCheckX, 0, 0), Vector2.down, groundCheckY, whatIsGround))
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    void Jump()
    {
            if (jumpBufferCounter > 0 && coyoteTimeCounter > 0 && !pState.jumping)
            {
                rb.velocity = new Vector3(rb.velocity.x, jumpForce);

                pState.jumping = true;
            }
            if (!Grounded() && airJumpCounter < maxAirJumps && Input.GetButtonDown("Jump"))
            {
                pState.jumping = true;

                airJumpCounter++;

                rb.velocity = new Vector3(rb.velocity.x, jumpForce);
            }

        if (Input.GetButtonUp("Jump") && rb.velocity.y > 3)
        {
            rb.velocity = new Vector2(rb.velocity.x, 0);

            pState.jumping = false;
        }

        anim.SetBool("Jumping", !Grounded());
    }

    void UpdateJumpVariables()
    {
        if (Grounded())
        {
            pState.jumping = false;
            coyoteTimeCounter = coyoteTime;
            airJumpCounter = 0;
        }
        else
        {
            coyoteTimeCounter -= Time.deltaTime;
        }

        if (Input.GetButtonDown("Jump"))
        {
            jumpBufferCounter = jumpBufferFrames;
        }
        else
        {
            jumpBufferCounter--;
        }
    }
}</code>

[Terence]

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::

The issue is with this line of SceneTransition:

StartCoroutine(UIManager.Instance.sceneFader.FadeAndLoadScene(SceneFader.FadeDirection.In, transitionTo));

More specifically, the sceneFader variable is null. This is because the variable in UIManager is initialised in Awake(), same as where the error occurs. For the code to go away, you need to ensure that UIManager.Awake() runs first before SceneTransition.Awake().

An easy way to do so is to change the Awake() in SceneTransition to Start(), so that it runs later.

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

public class SceneTransition : MonoBehaviour
{
    // Start is called before the first frame update

    [SerializeField] private string transitionTo;

    [SerializeField] private Transform startPoint;

    [SerializeField] private Vector2 exitDirection;

    [SerializeField] private float exitTime;

    private void AwakeStart()
    {
        if (GameManager.Instance.transitionedFromScene == transitionTo)
        {
            PlayerController.Instance.transform.position = startPoint.position;

            StartCoroutine(PlayerController.Instance.WalkIntoNewScene(exitDirection, exitTime));
        }

        StartCoroutine(UIManager.Instance.sceneFader.Fade(SceneFader.FadeDirection.Out));
    }

    private void OnTriggerEnter2D(Collider2D _other)
    {
        if (_other.CompareTag("Player"))
        {
            GameManager.Instance.transitionedFromScene = SceneManager.GetActiveScene().name;

            PlayerController.Instance.pState.cutscene = true;

            StartCoroutine(UIManager.Instance.sceneFader.FadeAndLoadScene(SceneFader.FadeDirection.In, transitionTo));
        }
    }
}

Let me know if this works.

[Bachok]

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Hello Terence! Thanks for the help, but unfortunately it won’t help, because it was Start() instead of Awake() from the very beginning, and I decided to replace it, thinking maybe it would help, but as you can see, for some reason, nothing happened, thank you anyway. Same message but with Start(): NullReferenceException: Object reference not set to an instance of an object SceneTransition.Start () (at Assets/code/SceneTransition.cs:20)

[Joseph Tang]

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I do believe that the issue is with your SceneFader. Yes, the error does indeed originate from SceneTransition.cs Awake(), but it is definitely in relation to your SceneFader not having it’s image component set yet.

If we look at your initial error, we receive a NullReferenceExceptionError pointing to the line calling UIManager’s sceneFader's Fade() function. This can only mean that:

1. UIManager doesn’t exist in the scene.
2. sceneFader doesn’t exist in the scene.
3. sceneFader’s Image can’t be reached.

The error is self explanatory, and the 3rd is possible due to the Fade() method’s only possible null error to be the image it’s setting.

---

So, my recommendation is to check for the following:

1. UIManager is in the scene. It only needs to be in the scene since the instance can be called once it’s there.
2. sceneFader is appropriately attached to the UIManager gameobject in the scene. Ensure that it actually is there in a playing game, there’s a possibility it isn’t and that will be a separate explorable problem.
3. sceneFader has an image component attached to it. This is important so that it can be referred to through the Fade() method.

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Now to actually solve this issue.

I think you should leave the SceneTransition.cs as Start(). Then set SceneFader.cs as Awake(). The true problem is likely the third issue if anything. Putting SceneTransition.cs as Start() will allow SceneFader.cs Awake() to run first, allowing the sceneFader to grab it’s image component in time for the Fade() method to work when called by SceneTransition.cs.

[Bachok]

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Hi, thanks, but I think it’s a problem in Unity itself, because at first everything was working perfectly for me, I wrote the code and added dimming to the scene and when I moved it dimmed, but after I started to make the lighting of the scene like sunlight or lighting places in caves through which you can move between locations, then when I started the game for the test, it started giving an error. So I think I messed up somewhere in Unity itself. Thank you for your help!

[Terence]

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Hi, thanks, but I think it’s a problem in Unity itself, because at first everything was working perfectly for me, I wrote the code and added dimming to the scene and when I moved it dimmed, but after I started to make the lighting of the scene like sunlight or lighting places in caves through which you can move between locations, then when I started the game for the test, it started giving an error. So I think I messed up somewhere in Unity itself. Thank you for your help!

Your code only works if the UIManager initialises script runs before the SceneTransition script. The error likely started occurring because the hierarchy of the GameObjects in your scene has changed, causing the ordering of the script to change as well.

Another thing you can look into is explicitly specifying which script should run before another by going to Project Settings > Script Execution Order.

[Bachok]

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Hello everyone again! I still can’t fix this game but I saw that after I changed Awake() back to Start() the error code changed and this is what it looks like after I did it – NullReferenceException: Object reference not set to an instance of an object SceneFader.SetColorImage (System.Single& _alpha, SceneFader+FadeDirection _fadeDirection) (at Assets/code/SceneFader.cs:71) SceneFader+<Fade>d__5.MoveNext () (at Assets/code/SceneFader.cs:40) UnityEngine.SetupCoroutine.InvokeMoveNext (System.Collections.IEnumerator enumerator, System.IntPtr returnValueAddress) (at <0652bf0e14024522b5c92574ad0ef550>:0) UnityEngine.MonoBehaviour:StartCoroutine(IEnumerator) SceneTransition:Start() (at Assets/code/SceneTransition.cs:27)

But what else I noticed in short I decided to delete the portal and when i started the game then it worked but for some reason the scene fader doesn’t go away so I can’t see anything I don’t know if this tells you anything or helps but just adding information. Thank you for your attention and thank you again for your help!

[Joseph Tang]

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Sorry, but I need confirmation that you’ve done this:

I was able to get the same error message as you did by changing my SceneFader.cs Awake() to Start().

So let’s put back the portal again. Then, again, I would like for you to set Both your

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SceneFader.cs

    // Start is called before the first frame update
    void Start Awake()
    {
        fadeOutUIImage = GetComponent<Image>();
    }

SceneTransition.cs

    private void Awake Start()
    {
        if (GameManager.Instance.transitionedFromScene == transitionTo)
        {
            PlayerController.Instance.transform.position = startPoint.position;

            StartCoroutine(PlayerController.Instance.WalkIntoNewScene(exitDirection, exitTime));
        }

        StartCoroutine(UIManager.Instance.sceneFader.Fade(SceneFader.FadeDirection.Out));
    }

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Again, if this is not the issue, please do tell. But first try to play with this script, then do not change it. If there are any errors, we can check up on those and continue forward using this script to check for any further issues.

• Terence

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[Bachok]

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Hello everyone! Thank you for your help! I finally did it, I had to rewrite the code because I guess something was wrong and replace the material in the Unity, but finally it works.

• Terence

has upvoted this post.

[Terence]

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Hello everyone! Thank you for your help! I finally did it, I had to rewrite the code because I guess something was wrong and replace the material in the Unity, but finally it works.

Bachok, can you elaborate more on this? What do you mean by replacing the material?

[Author]

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