[SOLVED] Object reference not set to an instance of an object

I'm trying to add listener to a button:

Code (CSharp):

1. void Start () {
2.         ...
3.         Button addButton = this.GetComponent<Button>();
4.         addButton.onClick.AddListener(AddButtonClicked);
5.     }

And getting this:

Code (CSharp):

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

 

addButton is null. check you added the Button component

 

I did.

 

Check if addButton is null in code. If it is, then you either have an extra copy of the script on something, or you have something setup wrong in your scene.

If neither of those is the case, then the error message is pointing towards another line.

 

It is NULL. Still can't understand why.

 

If GetComponent<Button>() is failing, then you don't have a Button component on your gameobject.

Is it in a child gameobject? If so, you should use GetComponentInChildren<Button>() instead.

GetComponent<Button>() only works if your script component and Button component are on the same game object.

 

I have Button and script on it, I even checked if there Button component on the Button.

 

Also, make sure you don't have another object in the scene with the script on it and no button component.

 

It is not null.
This gives nothing:

 if(addButton == null) print("addButton is NULL!!!!!!!");

And

print(addButton);

gives this:

AddButton (UnityEngine.UI.Button)

UnityEngine.MonoBehaviour:print(Object)

AddItem:Start() (at Assets/AddItem.cs:24)

 

Is AddButtonClicked a method or a delegate that gets assigned a method? If the former, check it's not null either:

Code (csharp):

1. print(AddButtonClicked==null?"Delegate not assigned.":"Delegate assigned.");

 

It's just a method.

 

At this point you're going to have to share your project, or at least a trimmed down version of your project because there's only so much anyone can do with the info you're drip feeding out.

 

Sanity check: Click once on the error in the console and ensure the object that's throwing the exception has a Button component (it may not be the object you think it is). It highlights yellow in the hierarchy when you click on it.

 

Scabbage thanks a lot , I did as you said.
The problem was that Text on Button had script attached.
Thanks everybody.

 

THANK YOU!!!

 

There's a pinned thread for this now:

How to fix a NullReferenceException error

https://forum.unity.com/threads/how-to-fix-a-nullreferenceexception-error.1230297/

Steps to success:
- Identify what is null
- Identify why it is null
- Fix that