How to Fix ‘NullReferenceException’ Error in Unity (Complete Beginner Guide)

If you’ve been developing games in Unity for even a short time, the NullReferenceException error has probably jumped out at you in bright red in the Console.
It’s one of the most common errors every Unity developer encounters—especially beginners.
The good news? It's also one of the easiest problems to fix once you understand what it means.

This guide explains why NullReferenceException happens, how to read the Console message, and the top methods to fix and prevent it.

✅ What Is “NullReferenceException” in Unity?

A NullReferenceException happens when your script tries to use a reference that doesn’t exist.

In simple words:

Unity expected something, but it was empty (null).

Example:
If you say:

player.health = 100;

…but player is empty, Unity throws:

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

🎯 Common Causes of NullReferenceException

Here are the top 6 reasons this error appears:

1️⃣ You forgot to assign a GameObject or Component in the Inspector

This is the #1 beginner mistake.

Example:

public GameObject player;

If “player” is empty in the Inspector → Error!

2️⃣ You used GetComponent but the component doesn’t exist

player = GetComponent<Rigidbody>();

But if the GameObject does NOT have a Rigidbody → Null.

3️⃣ Script execution order issue

You try to use something in Start() that gets initialized in another script’s Start() — but Unity hasn’t run it yet.

4️⃣ Object was destroyed before using it

Destroy(enemy); enemy.TakeDamage();

You destroyed it… then used it.

5️⃣ Array or List element is empty

weapons[0].Shoot();

But weapons[0] is null → Error.

6️⃣ You tried to find an object that doesn’t exist

Example:

GameObject.Find("Player");

If the Player is NOT named exactly "Player" → returns null.

🛠️ How to Fix NullReferenceException in Unity (Step-by-Step)

Let’s walk through the exact method professionals use to find and fix this error.

STEP 1: Double-click the error in the Console

Unity will highlight the exact line inside the script that caused the issue.

• This line usually tells you:
• Which variable is null
• Which script caused it
• Where it happened

STEP 2: Identify which variable is NULL

Take this example:

player.health = 50;

Either:

player is null
OR

player.health is null

To check, you can temporarily add:

Debug.Log(player); Debug.Log(player.health);

Unity will show which one prints null.

STEP 3: Fix the Assignment

Depending on the issue, here’s how to fix it:

✔️ Fix #1 — Assign the reference in the Inspector

If you have something like:

public GameObject player;

Make sure you drag your Player object onto the field in the Inspector.

✔️ Fix #2 — Use GetComponent properly

Correct:

playerRb = GetComponent<Rigidbody>();

But if the component is on a child object:

playerRb = GetComponentInChildren<Rigidbody>();

Or somewhere else:

playerRb = player.GetComponent<Rigidbody>();

✔️ Fix #3 — Check if object was destroyed

Use:

if(enemy != null) {    enemy.TakeDamage(); }

✔️ Fix #4 — Use Awake() for early initialization

If two scripts depend on each other:

Use Awake() to initialize variables

Use Start() to use them

✔️ Fix #5 — Ensure Find() actually finds something

Always check:

player = GameObject.Find("Player"); if(player == null)    Debug.LogError("Player not found!");

✔️ Fix #6 — Check your List / Array values

If you have:

weapons[0].Shoot();

Make sure weapons[0] is assigned in Inspector or script.

✔️ Bonus: Best Practices to Avoid NullReferenceException Forever

1. Always use Null Checks

if(myObject != null) {    myObject.DoSomething(); }

2. Initialize variables when declaring

private List<int> scores = new List<int>();

3. Avoid GameObject.Find() in runtime

Use SerializeField instead:

[SerializeField] private Player player;

4. Use TryGetComponent

if(TryGetComponent(out Rigidbody rb)) {    rb.AddForce(Vector3.up * 10f); }

5. Use Debug.Log often when testing

This is the fastest way to catch nulls before they break gameplay.

🎉 Final Thoughts

NullReferenceException is annoying—but it’s also a great learning tool.
Once you understand how references work, fixing this error becomes incredibly easy.

With the steps above:

• You’ll know exactly what to check
• You’ll fix null issues in seconds
• You’ll avoid 90% of beginner mistakes
• Master this, and your Unity development speed will improve dramatically.