Can't add UnityAction to a list of UnityActions not working

The class BattleEnemy has a List named attackList, and antoher UnityAction named first.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;

public class BBlackout : BattleEnemy
{
    private void HeadButt()
    {
        Debug.Log("Headbutt");
    }

    private void Start()
    {
        first = HeadButt;
        attackList.Add(first); //first attempt
        attackList.Add(HeadButt); //second attempt
    }
}

When either of the attempts are run, the debug window writes “NullReferenceException: Object reference not set to an instance of an object.”

Is there a specific way I am supposed to add UnityActions to a list?,The class BBlackout inherits from BattleEnemy. BattleEnemy has a List named attacklist, and a UnityAction named first.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;

public class BBlackout : BattleEnemy
{
    private void HeadButt()
    {
        Debug.Log("Headbutt");
    }

    private void Start()
    {
        first = HeadButt;
        attackList.Add(first); //first attempt
        attackList.Add(HeadButt); //second attempt
    }
}

But when this code runs, the Debug menu writes “NullReferenceException: Object reference not set to an instance of an object” with either of those being used.

Is there a specific way I am supposed to add UnityActions into a list?

In the Start() method you should initialize your list first.
Like so:

     private void Start()
     {
         attackList = new List<UnityAction>();

         first = HeadButt;
         attackList.Add(first); //first attempt
         attackList.Add(HeadButt); //second attempt
     }

When you create a list it is by default set to Null. So that’s why you get this “NullReferenceException”.