Object reference not set to reference of an object

[MJamPeanut]

I’m trying to clamp a planet’s x axis between two values but I keep getting errors. Planet2’s value is not null

Here’s my code:

 if (planet2.eulerAngles.x < -90)
     planet2.eulerAngles = new Vector3(-90, 0, 0);
if (planet2.eulerAngles.x > 90)
     planet2.eulerAngles = new Vector3(90, 0, 0);

It gives me the object reference error during runtime, and whenever the planet reaches the bound, it jumps to another location. Yes, I tried Mathf.Clamp, but it did exactly the same thing.

[Kurt-Dekker]

None of that matters.

NullReference is the single most common error while programming. Fixing it is always the same.

• also known as: Unassigned Reference Exception
• also known as: Missing Reference Exception
• also known as: Object reference not set to an instance of an object

Don’t waste your life spinning around and round on this error. Instead, learn how to fix it fast… it’s EASY!!

Some notes on how to fix a NullReferenceException error in Unity3D:

http://plbm.com/?p=221

The basic 3 steps outlined above are:

1. Identify what is null ← any other action taken before this step is WASTED TIME
2. Identify why it is null
3. Fix that.

Expect to see this error a LOT. It’s easily the most common thing to do when working. Learn how to fix it rapidly. It’s easy. See the above link for more tips.

You need to figure out HOW that variable is supposed to get its initial value. There are many ways in Unity. In order of likelihood, it might be ONE of the following:

• drag it in using the inspector
• code inside this script initializes it
• some OTHER external code initializes it
• ? something else?

This is the kind of mindset and thinking process you need to bring to this problem:

Why do my Music ignore the Sliders ?

Let me take you step by step through it. You see the error line, line 35? The only possible thing that could be null in that line is audio_BGMusic So that’s part 1. That’s what’s null. We identified it. Part 2… WHY is it null? Well, first we start with “who is supposed to make it not null?” Looking up further I see line 19 sets it, with this construct: audio_BGMusic = ObjectMusic.GetComponent<AudioSource>(); So lets take that apart. How can that fail? We have to suppose it DID fail, so we…

Step by step, break it down, find the problem.

Here is an analogy of a null reference:

• I give you an empty cookie jar
• I tell you to take a cookie from the jar

Your job is to identify which jar is empty, find out why it is empty, and fix that.

[MJamPeanut]

I know what a null reference error is, I just can’t find what object is null, the only variable on the line listed in the error is planet2, which I know is not null as it rotates correctly when I tell it to.

[vertxxyz]

The error can’t be wrong, so do some debugging and confirm what’s going on.

You’re probably just making an assumption and perhaps there’s just two scripts in the scene, one assigned and one null. You can find this out yourself by debugging.

[JoshuaMcKenzie]

then add a null check a line before the error and when null issue a Debug.LogError("planet2 is null,this);

The “this” is in the context parameter (e.g. the monobehaviour instance the logerror was called in) which means when you click on the log unity’s console it will highligh the exact gameobject with the monobehaviour throwing the exception.

there you can check if its the script you are thinking of or if some duplicate script is getting created and thats what throwing the error

[MJamPeanut]

Thanks, I tried that and discovered that Earth was indeed null. So I looked at the other function where planet2 was defined:

planet2 = GameObject.Find("Earth").transform;

and then noticed that the function didn’t get called until later on, so that’s why it was null.
I can be so dumb sometimes.

[Kurt-Dekker]

@MJamPeanut

GameObject.Find("Earth").transform;

IF you ever find yourself writing code like the above ^ ^ ^… just don’t do it!!

Remember the first rule of GameObject.Find():

Do not use GameObject.Find();

More information: Regarding GameObject.Find · UnityTipsRedux

Why cant i find the other objects?

As Spiney says above, reference it by a master script, like this one I might use for my player: using System.Collections; using System.Collections.Generic; using UnityEngine; // @kurtdekker - put this on the root of your player. // It does NOTHING except give you quick access // to other parts of the player. // // For instance, your player hierarchy might look like: // // PlayerPrefab // VisibleAnimatedGeometry // Weapon1 // Weapon2 // DialogPopup public class …

In general, DO NOT use Find-like or GetComponent/AddComponent-like methods unless there truly is no other way, eg, dynamic runtime discovery of arbitrary objects. These mechanisms are for extremely-advanced use ONLY.

If something is built into your scene or prefab, make a script and drag the reference(s) in. That will let you experience the highest rate of The Unity Way™ success of accessing things in your game.

“Stop playing ‘Where’s GameWaldo’ and drag it in already!”

Here’s why all this stuff is CRAZY code:

SetActive(false) on Start() only working on Unity editor, but not on build target

Definitely get away from all that FindTag silliness. There is absolutely NO reason you need that. Put the Tutorial script on its own object, drag all the items into an array, just like you do for any other Unity dragged-in reference, then make an API on the tutorial that lets you show only one of them. If you have an array: [Header( "Drag each tutorial part in here in order.")] public GameObject[] AllTutorialPartsInOrder; then a function to switch them on one at a time is: public void Selec…