Can't get SceneManager.LoadScene to work properly

Unity Engine
1

I have a script that’s supposed to load the next level when a player reaches a checkpoint, but for some reason, when I tested it on level 1, it worked just fine, the player touched the checkpoint, a transition happened and the next level loaded, but for some reason on level 2, everything works fine, except it just reloads level 2, rather than going to level 3, I have the exact same script attached in both scenes to the checkpoint, could someone help?

here’s my script btw

using UnityEngine;
using UnityEngine.SceneManagement;
using System.Collections;

public class DoorCollision : MonoBehaviour
{
    public Animator animator;

    public Animator TransitionAnim;

    public GameObject playerRef;

    IEnumerator MakeTransition()
    {
        TransitionAnim.SetTrigger("Start");

        yield return new WaitForSeconds(1);

        SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex + 1, LoadSceneMode.Single);
    }

    private void OnTriggerEnter2D(Collider2D hitInfo)
    {
        if (hitInfo.CompareTag("Player"))
        {
            playerRef.transform.position = new Vector3(0, -1.2f, 0);
            animator.SetBool("DoorOpened", true);
            StartCoroutine(MakeTransition());
        }
    }
}
2

Avoid hairy lines like line 19 above. There is no easy way to get any intel about what numbers it is thinking is index + 1, which is really the ONLY piece of data you care about getting correct.

Instead, break it up:

How to break down hairy lines of code:

http://plbm.com/?p=248

Break it up, practice social distancing in your code, one thing per line please.

Beyond that, to understand this further, what is often happening in these cases is one of the following:

  • the code you think is executing is not actually executing at all
  • the code is executing far EARLIER or LATER than you think
  • the code is executing far LESS OFTEN than you think
  • the code is executing far MORE OFTEN than you think
  • the code is executing on another GameObject than you think it is

To help gain more insight into your problem, I recommend liberally sprinkling Debug.Log() statements through your code to display information in realtime.

Doing this should help you answer these types of questions:

  • is this code even running? which parts are running? how often does it run? what order does it run in?
  • what are the values of the variables involved? Are they initialized? Are the values reasonable?
  • are you meeting ALL the requirements to receive callbacks such as triggers / colliders (review the documentation)

Knowing this information will help you reason about the behavior you are seeing.

You can also put in Debug.Break() to pause the Editor when certain interesting pieces of code run, and then study the scene

You could also just display various important quantities in UI Text elements to watch them change as you play the game.

If you are running a mobile device you can also view the console output. Google for how on your particular mobile target.

Here’s an example of putting in a laser-focused Debug.Log() and how that can save you a TON of time wallowing around speculating what might be going wrong:

3

just to add, check:
1 - are all your relevant scenes included in your build settings
2 - are the scenes in the order you expect them to be

4

The alternative is to use addressables and addressable references to load scenes, rather than rely specifically on a fragile set-up of build index and order of scenes.

5

Thanks everyone! I’ll be sure to try your advice