Error with Event Trigger

Hey,

I have some code for dragging inventory items however whenever I click play and open up the inventory, unity crashes with the error:

"NullReferenceException: Object reference not set to an instance of an object
DisplayInventory.AddEvent (UnityEngine.GameObject obj, UnityEngine.EventSystems.EventTriggerType type, UnityEngine.Events.UnityAction`1[T0] action) (at Assets/Scripts/Inventory/DisplayInventory.cs:76)
DisplayInventory.CreateSlots () (at Assets/Scripts/Inventory/DisplayInventory.cs:38)
DisplayInventory.Start () (at Assets/Scripts/Inventory/DisplayInventory.cs:20)"

If I blank out this line: "AddEvent(obj, EventTriggerType.BeginDrag, delegate { OnDragStart(obj); });"
then the inventory works fine again, however I can't drag items.

Does anyone know why this line is causing a crash?

 

The good news is that it doesn't matter what you're doing.

Why?

The answer is always the same... ALWAYS. It is the single most common error ever.

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
- 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

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

The basic steps outlined above are:
- Identify what is null
- Identify why it is null
- 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:

https://forum.unity.com/threads/why-do-my-music-ignore-the-sliders.993849/#post-6453695

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

Here is a clean analogy of the actual underlying problem of a null reference exception:

https://forum.unity.com/threads/nul...n-instance-of-an-object.1108865/#post-7137032