Bug GUILayout.Window -> Resolve of invalid GC handle. The handle is from a previous domain. The resolve

Hello,

BUG

With an EditorWindow utilizing GUILayout.Window, Unity throws the following error when entering play mode if that Editor Window is open:

Code (CSharp):

1. Resolve of invalid GC handle. The handle is from a previous domain. The resolve operation is skipped.
2. UnityEngine.GUILayout:Window (int,UnityEngine.Rect,UnityEngine.GUI/WindowFunction,string,UnityEngine.GUILayoutOption[])
3. SomeEditor:OnGUI () (at Assets/Editor/SomeEditor.cs:14)
4. UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&)

---

REPRODUCTION

This can be reproduced with the following simple script in an otherwise empty project:

Code (CSharp):

1. using UnityEngine;
2. using UnityEditor;
3.  
4. public class SomeEditor : EditorWindow
5. {
6.  
7.     [MenuItem("Tools/SomeEditor")]
8.     public static void ShowWindow() {
9.         GetWindow<SomeEditor>().Show();
10.     }
11.  
12.     void OnGUI() {
13.         BeginWindows();
14.         GUILayout.Window(0, new Rect(20, 20, 20, 20), WindowCallback, "Hello");
15.         EndWindows();
16.     }
17.  
18.     void WindowCallback(int ID) {
19.         GUILayout.Label("Error on enter/exit play mode");
20.     }
21. }

1. Import the attached script (or copy/paste the code above).
2. Open the EditorWindow ("Tools/SomeEditor").
3. Enter play mode with the EditorWindow open.

Tested in Unity 2021 and 2022. This error was not present in Unity 2019.

Thank you.

 

I have noticed exactly the same thing, using 2020.3.42f1. (Haven't made a minimal example though)

 

Same here. Might be related to this issue below.

https://issuetracker.unity3d.com/is...en-exiting-play-mode-after-creating-a-tilemap