Unity Hangs on SceneManager.UnloadScene()

(Version: Unity 5.3.0f4 Personal)

I'm just getting started with Additive scene loading, and have hit an issue where Unity is hanging when I try to unload a scene with OnTriggerEnter or OnTriggerExit. The goal is to set up trigger colliders throughout my "Hub Room" which will load objects from other scenes or unload them if already loaded, when the player hits a trigger.

The code to load objects from "Spoke Room 01" into my Hub room on trigger enter looks like this:

Code (CSharp):

1. void OnTriggerEnter(Collider other) { // Same result when using OnTriggerExit btw
2.     if (other.gameObject.CompareTag("Player")) {
3.        if (SceneManager.GetSceneByName("Spoke Room 01").isLoaded == false) {
4.           // This works
5.           SceneManager.LoadScene("Spoke Room 01", LoadSceneMode.Additive);
6.             } else  {
7.                 // This hangs Unity
8.                 SceneManager.UnloadScene("Spoke Room 01");
9.             }
10.         }
11.     }

The new scene and its objects are loaded fine into the Hub on first collision with the trigger (and shows up in the Hierarchy at runtime, but Unity hangs (instead of unloading the new scene) if the new scene is already loaded and the player collides with the trigger. One thing I did to troubleshoot was use a keypress to manually unload the new scene, which worked fine. Any followup questions or suggestions for further troubleshooting are appreciated. Thanks!

 

@Jordi Bonastre - thanks very much. In the meantime, I will see if I can find a workaround and will share anything useful I discover.

 

Good call, @SteenLund -- I just tried this out and it seems to help. Level is loaded and unloaded without any issues. Thanks!

Code (CSharp):

1. void OnTriggerEnter(Collider other) {
2.         if (other.gameObject.CompareTag("Player")) {
3.             if (SceneManager.GetSceneByName("Spoke Room 01").isLoaded == false) {
4.                 StartCoroutine("LoadSubScene");
5.             } else if (SceneManager.GetSceneByName("Spoke Room 01").isLoaded == true) {
6.                 StartCoroutine("UnloadSubScene");
7.             }
8.         }
9. }
10.  
11. IEnumerator LoadSubScene() {
12.         yield return new WaitForSeconds(.10f);
13.         SceneManager.LoadScene("Spoke Room 01", LoadSceneMode.Additive);
14. }
15. IEnumerator UnloadSubScene() {
16.         yield return new WaitForSeconds(.10f);
17.         SceneManager.UnloadScene("Spoke Room 01");
18. }

 

Hello,

Ive just been struggling with this too until I found this thread. Thanks for the workaround.

 

I just reported an issue under #783271 with a crash in UnloadScene (that was loaded additive) instead of a hang and also in a coroutine (but which was started from a trigger callback).

Not sure its the same error, but suspicious simillarities...

 

Unfortunately, that doesn't work for me. I mean... It works in editor, but still crashing in standalone windows x86 exe.

 

I can confirm that this works.
I was trying to unload a scene OnTrigger, unity did nothing but hang.
I used an Enumerator and waited for 0.1 second or so before making the call and it worked!

Please fix the bug asap though.

 

"Destroying GameObjects immediately is not permitted during physics trigger/contact or animation event callbacks"
+1 would like it to be patched

 

We are also having this problem with 5.4b19.

 

Any news @SteenLund ? Still crashes in Unity 5.4.0f3

 

To which Version? UnloadSceneAsync is not present in 5.4.1p1

 

What 5.4 version? Can you support UnloadAsync Also?

 

The documentation doesn't mention anything about throwing exceptions so I would like to get some clarification. Are the following two statements are correct?
UnloadScene() may throw an exception.
UnloadSceneAsync() will not throw an exception.