);
return FMOD.RESULT.OK;
}
public void Start()
{
FMOD.Studio.EventInstance instance;
if (stoppedInstances.Count == 0)
AddInstance();
instance = stoppedInstances.Pop();
FMODUnity.RuntimeManager.AttachInstanceToGameObject(instance, transform, (Rigidbody2D)null);
instance.start();
}
}
```
---
### Author:  [@cameron-fmod](https://qa.fmod.com/u/cameron-fmod)
#### Post date: [April 15, 2021, 3:50am UTC](https://qa.fmod.com/t/unityeditor-crashes-on-eventinstance-callback/17018/2 "2021-04-15T03:50:52Z")
What versions of FMOD and Unity are you using?
When I try your script I do get:
```auto
UnityException: FindObjectsOfTypeAll is not allowed to be called from a MonoBehaviour constructor (or instance field initializer), call it in Awake or Start instead.
```
Which is due to the `FMODUnity.RuntimeManager` being called (and created) in the constructor, if the script is attached to a gameObject.
Are you able to get any meaningful info from the crash logs at all?
---
### Author:  [@verodicia](https://qa.fmod.com/u/verodicia)
#### Post date: [April 20, 2021, 6:14am UTC](https://qa.fmod.com/t/unityeditor-crashes-on-eventinstance-callback/17018/3 "2021-04-20T06:14:33Z")
Hello, Sorry for the late response, I’m unable to upload the crash log files here ([Crash\_2021-04-19\_153046519.rar - Google Drive](https://drive.google.com/file/d/15CcK77dihHx-TJ_U-M4H6tZe8ofb-rl8/view?usp=sharing)).
> Unknown caused an Access Violation (0xc0000005)
> in module Unknown at 0033:611109c1.
I’m using Unity 2019.4.22.f1 LTS release, I believe my FMOD version is 2.0.08, 64x, Build#114339.
Apologies for not providing the full source code, you can find the unity project here: [GitHub - Light7734/Unity-Managers: A project with manager classes and tidy folder structure to start your 2d project with.](https://github.com/Light3039/Unity-Managers)
(Audio scripts are in Assets/Scripts/Audio/…)
You can crash the editor by spamming the 3 buttons in the middle, it crashes randomly when a sound stops.
I don’t get the UnityException you’ve mentioned, I think it’s because I use this class to create AudioEventFXInstance:
I’m not sure whether or not my appraoch is corerct.
```
public class AudioEmitterFX : MonoBehaviour
{
[SerializeField]
private AudioEmitterData data; // struct that holds an array of string(fmod event)
private Dictionary events = new Dictionary();
private void Awake()
{
for (int i = 0; i < data.events.Length; i++)
{
events[data.events[i].Substring(data.events[i].LastIndexOf("/") + 1)] = new AudioEventFXInstance(transform, data.events[i]);
Debug.Log(data.events[i] + " - > " + data.events[i].Substring(data.events[i].LastIndexOf("/") + 1));
}
Debug.Log(events);
}
public AudioEventFXInstance this[string name]
{
get { return events[name]; }
}
}
```
---
### Author:  [@cameron-fmod](https://qa.fmod.com/u/cameron-fmod)
#### Post date: [April 22, 2021, 1:00am UTC](https://qa.fmod.com/t/unityeditor-crashes-on-eventinstance-callback/17018/4 "2021-04-22T01:00:51Z")
This appears to be cause by the callback delegate being garbage collected, because it is not being cached the garbage collector will come along (at a seemingly random time) and it will appear to be unreferenced so it will be removed.
In general with callbacks, we recommend doing three things:
- Cache the delegate, this will stop the garbage collector from removing the callback.
- Make callback functions static.
- Functions require the `[MonoPInvokeCallback]` attribute.
This is mentioned in the [Platform Specifics (callbacks on ahead of time compile platforms)](https://fmod.com/resources/documentation-unity?version=2.2&page=platform-specifics.html#callbacks-on-ahead-of-time-compile-platforms) section in our docs.