Good evening everyone, I’m a Unity beginner and I’m following a tutorial to learn how to create an RPG.
So far I have not had any problems, I have been able to execute the lessons successfully.
However, after completing step 9.2 without problems to, getting the same result as the teacher. I saved my project and rebooted Unity. When i open the project and play, a new error has been displayed on the console.
As I did the tutorial three times to make sure I had not made any mistakes, I was able to record a short video in which I complete the tutorial and restart Unity. WATCH
"
NullReferenceException: Object reference not set to an instance of an object
UIManager.SetUseable (ActionButton btn, IUseable useable) (at C:/Users/Mystic Rabbit/Desktop/GameMaker/RPG v9.1/RPG/Assets/Scripts/Managers/UIManager.cs:112)
UIManager.Start () (at C:/Users/Mystic Rabbit/Desktop/GameMaker/RPG v9.1/RPG/Assets/Scripts/Managers/UIManager.cs:54)
"
I’m leaving the youtube link with the exact step of the tutorial I’m having problem. This will make it easier to understand the situation. I am also leaving the script pointed out by the error, so that you can analyze.
Remember, I did every tutorial 9.2, until the last second, I got the same positive results as the teacher in the video, but after restarting the software, this error appeared on the console.
Since I got a positive result, I think it’s a problem with Unity. I also tried “Rebuild Solution” but I could not fix this error.
Please someone help me, as I said I’m a beginner, I’m taking my first steps and I can not do it alone 
using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
public class UIManager : MonoBehaviour
{
private static UIManager instance;
public static UIManager MyInstance
{
get
{
if (instance== null)
{
instance = FindObjectOfType<UIManager>();
}
return instance;
}
}
/// <summary>
/// A reference to all the action buttos
/// </summary>
[SerializeField]
private ActionButton[] actionButtons;
[SerializeField]
private GameObject targetFrame;
private Stat healthStat;
[SerializeField]
private Image portraitFrame;
[SerializeField]
private CanvasGroup keybindMenu;
private GameObject[] keybindButtons;
private void Awake()
{
keybindButtons = GameObject.FindGameObjectsWithTag("Keybind");
}
// Use this for initialization
void Start()
{
healthStat = targetFrame.GetComponentInChildren<Stat>();
SetUseable(actionButtons[0], SpellBook.MyInstance.GetSpell("Fireball"));
SetUseable(actionButtons[1], SpellBook.MyInstance.GetSpell("Frostbolt"));
SetUseable(actionButtons[2], SpellBook.MyInstance.GetSpell("Thunderbolt"));
}
// Update is called once per frame
void Update()
{
if (Input.GetKeyDown(KeyCode.Escape))
{
OpenCloseMenu();
}
}
public void ShowTargetFrame(NPC target)
{
targetFrame.SetActive(true);
healthStat.initialized(target.MyHealth.MyCurrentValue, target.MyHealth.MyMaxValue);
portraitFrame.sprite = target.MyPortrait;
target.healthChanged += new HealthChanged(UpdateTargetFrame);
target.characterRemoved += new CharacterRemoved(HideTargetFrame);
}
public void HideTargetFrame()
{
targetFrame.SetActive(false);
}
public void UpdateTargetFrame(float health)
{
healthStat.MyCurrentValue = health;
}
public void OpenCloseMenu()
{
keybindMenu.alpha = keybindMenu.alpha > 0 ? 0 : 1;
keybindMenu.blocksRaycasts = keybindMenu.blocksRaycasts == true ? false : true;
Time.timeScale = Time.timeScale > 0 ? 0 : 1;
}
public void UpdateKeyText(string key, KeyCode code)
{
Text tmp = Array.Find(keybindButtons, x => x.name == key).GetComponentInChildren<Text>();
tmp.text = code.ToString();
}
public void CLickActionButton(string buttonName)
{
Array.Find(actionButtons, x => x.gameObject.name == buttonName).MyButton.onClick.Invoke();
}
public void SetUseable(ActionButton btn, IUseable useable)
{
btn.MyButton.image.sprite = useable.MyIcon;
btn.MyButton.image.color = Color.white;
btn.MyUseable = useable;
}
}
Edit: I guess you’d have instance a static member for that to work.
