Can't get method on CallableCustom "Delegate::Invoke" error when building/debugging .NET project

[RIKDXHQ11]

Godot version

4.0beta

System information

windows10,NVIDIA GeForce GTX 1660,Vulkan API 1.2.0

Issue description

GODOT BETA 7.0 C # version, when debugging for many times, suddenly stuck, the debugging progress bar did not respond, and then if the program was not forced to close in time, the entire operating system would crash.
But there is no error prompt,
After I restart the computer, a lot of errors will occur when I open the project:

  modules/mono/managed_callable.cpp:92 - Condition "delegate_handle.value == nullptr" is true.
  Can't get method on CallableCustom "Delegate::Invoke".
  core/object/object.cpp:1058 - Error calling from signal 'timeout' to callable: 'Node::': Method not found.
  modules/mono/managed_callable.cpp:92 - Condition "delegate_handle.value == nullptr" is true.
  Can't get method on CallableCustom "Delegate::Invoke".
  core/object/object.cpp:1058 - Error calling from signal 'timeout' to callable: 'Node::': Method not found.
  modules/mono/managed_callable.cpp:92 - Condition "delegate_handle.value == nullptr" is true.
  Can't get method on CallableCustom "Delegate::Invoke".
  core/object/object.cpp:1058 - Error calling from signal 'timeout' to callable: 'Node::': Method not found.
  modules/mono/managed_callable.cpp:92 - Condition "delegate_handle.value == nullptr" is true.
  Can't get method on CallableCustom "Delegate::Invoke".
  core/object/object.cpp:1058 - Error calling from signal 'timeout' to callable: 'Node::': Method not found.
  modules/mono/managed_callable.cpp:92 - Condition "delegate_handle.value == nullptr" is true.
  Can't get method on CallableCustom "Delegate::Invoke".
  core/object/object.cpp:1058 - Error calling from signal 'timeout' to callable: 'Node::': Method not found.
  modules/mono/managed_callable.cpp:92 - Condition "delegate_handle.value == nullptr" is true.
  Can't get method on CallableCustom "Delegate::Invoke".
  core/object/object.cpp:1058 - Error calling from signal 'timeout' to callable: 'Node::': Method not found.
  modules/mono/managed_callable.cpp:92 - Condition "delegate_handle.value == nullptr" is true.

Deleting the godot folder can solve the problem, but it will seriously affect my computer health and my spirit.
I'm going crazy.
Please solve this problem, otherwise it will become difficult to use, thank you.

Steps to reproduce

N/A

Minimal reproduction project

N/A

[matthew798]

Just wanted to chime in and say that I am also facing this issue and it's blocking. I'm using the official build of beta 9. Not complaining or anything, I know it's beta :).

Is this related to, but not fixed by #69194? If so, do we know how to work around it for the time being?

[matthew798]

Just wanted to provide some more context:

This issue occurs for me only when a C# script marked as [Tool] is attached to a node, and the script loads 1 or more resources.

Here is the code that causes the error, in my case:

[Tool]
public partial class LevelManager : Node3D
{
	public override void _Ready()
	{
	    LoadBlocks();
		
	    if(_levelNode == null){
		_levelNode = new Node3D() {Name = "Level"};
		AddChild(_levelNode);
		if(Engine.IsEditorHint()){
			_levelNode.Owner = this;
		}
	    }
	    LoadLevel();
	}
        
        private void LoadBlocks(string path = "Prefabs/Blocks"){
	    _blockList.Clear();

	    var files = Directory.GetFiles(path, "*.tscn", SearchOption.AllDirectories);

	    foreach(String file in files){
		var filename = Path.GetFileNameWithoutExtension(file);
		_blockList[filename] = GD.Load<PackedScene>($"res://{path}/{filename}.tscn");
	    }
	}
}

If either the [Tool] attribute is removed or the LoadBlocks method is commented out, the issue does not occur. I hope this helps.

I was running into this. In my case it seems to have been caused by using a .NET 7 SDK instead of .NET 6. dotnet defaults to using the latest installed SDK and I have both installed. Adding the following global.json file to the root of the project fixed the issue.

{
  "sdk": {
    "version": "6.0.404"
  }
}

Currently running Godot 4 Beta 10 on MacOS Ventura 13.0.1.

[gallsy]

{
  "sdk": {
    "version": "6.0.404"
  }
}

This unfortunately hasn't fixed it in my case. On the next build after launching I get the same error as above.
The messages from the terminal are:

Copying Godot Offline Packages...
Unloading assembly load context...
Assembly unloading is taking longer than expected...
Failed to unload assemblies. Possible causes: Strong GC handles, running threads, etc.
ERROR: .NET: Failed to unload assemblies.
   at: (modules/mono/mono_gd/gd_mono.cpp:504)
ERROR: Condition "delegate_handle.value == nullptr" is true.
   at: call (modules/mono/managed_callable.cpp:92)
ERROR: Can't get method on CallableCustom "Delegate::Invoke".
   at: (core/variant/callable.cpp:333)
ERROR: Error calling from signal 'timeout' to callable: 'Node::': Method not found.

I'm running:
4.0.beta10.mono (As far as I can tell this has affected every build since the .net 6 merge.)
Windows 10 pro x64

dotnet --info shows:
.NET SDKs installed:
2.1.202 [C:\Program Files\dotnet\sdk]
2.1.401 [C:\Program Files\dotnet\sdk]
2.1.402 [C:\Program Files\dotnet\sdk]
2.1.526 [C:\Program Files\dotnet\sdk]
3.1.120 [C:\Program Files\dotnet\sdk]
3.1.201 [C:\Program Files\dotnet\sdk]
3.1.426 [C:\Program Files\dotnet\sdk]
5.0.104 [C:\Program Files\dotnet\sdk]
5.0.408 [C:\Program Files\dotnet\sdk]
6.0.112 [C:\Program Files\dotnet\sdk]
6.0.307 [C:\Program Files\dotnet\sdk]
6.0.400 [C:\Program Files\dotnet\sdk]
6.0.404 [C:\Program Files\dotnet\sdk]

[matthew798]

@gallsy can you confirm that you are running a [Tool] script and it loads a resource from disk?

[gallsy]

@matthew798 yes that's right.
The problem seems to be caused by my C# plugin using [Tool] and has multiple references to scenes via ResourceLoader.Load<PackedScene>("uid://whatever") and json files via

var fileStream = FileAccess.Open(filePath, FileAccess.ModeFlags.Read);
var fileText = fileStream.GetAsText();
fileStream.Dispose();

The only external dependency I'm using is Newtonsoft.Json.

[guessy42]

Been hit by this myself in beta 9.0

I had some [Tool] scripts, but removing [Tool] did not fix the issue.

It appears to be being caused by assemblies not getting unloaded properly. From the godot console:

Unloading assembly load context...
Vulkan API 1.3.205 - Using Vulkan Device #0: NVIDIA - NVIDIA GeForce GTX 1050 Ti

<some game logging stuff here>
Assembly unloading is taking longer than expected...
Failed to unload assemblies. Possible causes: Strong GC handles, running threads, etc.

The deluge of errors starts immediately thereafter.

In my case, I can cause this to happen by:

1. Starting up the editor
2. You can build/run the project as much as you like without issue here
3. Make a change to the code that forces script recompilation
4. Something somewhere will kick up an exception in ScriptManagerBridge.TryReloadRegisteredScriptWithClass to do with adding a type to a dictionary that already contains that given key, always a generic class:

  modules/mono/glue/runtime_interop.cpp:1223 - System.ArgumentException: An item with the same key has already been added. Key: DisplayControlCollection`2[PawnSystem.Pawn,ClientControllerSystem.PawnUIControl]
     at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
     at System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value)
     at Godot.Bridge.ScriptManagerBridge.ScriptTypeBiMap.Add(IntPtr scriptPtr, Type scriptType) in /root/godot/modules/mono/glue/GodotSharp/GodotSharp/Core/Bridge/ScriptManagerBridge.types.cs:line 23
     at Godot.Bridge.ScriptManagerBridge.TryReloadRegisteredScriptWithClass(IntPtr scriptPtr) in /root/godot/modules/mono/glue/GodotSharp/GodotSharp/Core/Bridge/ScriptManagerBridge.cs:line 545

5. Project can still run etc as many times as you like
6. At the next script recompilation, the assembly fails to unload as described above and it all goes to hell

Curiously, only building from visual studio code (as opposed to the godot editor) sees the issue with TryReloadRegisteredScriptWithClass and generic classes kick off immediately. The second time you build from VSCode, either the deluge begins in the godot editor or it just outright freezes, but so long as you don't need to edit scenes you can still work and run the project just fine from visual studio code.

[guessy42]

Quick update, I've had some luck tracking this down!

The cause - in my case - appeared to be, as the 'failed to unload assemblies' message mentioned, strong GC handles. Specifically, static variables that would persist between reloads and potentially have handles to things that should have been deleted.

The quick tl;dr, manage your static variables responsibly. I had a few things static that really didn't need to be, and after refactoring I can no longer reproduce the error as I mentioned previously.

[matthew798]

@guessy42 Interesting. I'd be curious to see what the before and after of your refactoring look like. I don't see how a static variable would cause an issue here. Also, I don't have any static variables in my script.

[guessy42]

@guessy42 Interesting. I'd be curious to see what the before and after of your refactoring look like. I don't see how a static variable would cause an issue here. Also, I don't have any static variables in my script.

It could also be static events, or really anything that creates a strong handle that stops the assembly from being unloaded. To be honest, I'm not 100% sure what all the possible causes for stopping assemblies unloading even are.

This is the original, problematic script: https://pastebin.com/Ey7XQtGH
This is the fixed one: https://pastebin.com/PjG67QEr

It's pretty much moving static variables to singleton instance variables and adding more cleanup / safeguards. Awaiters is an autoload.

In hindsight the use of static variables in that script was honestly bound to cause problems but, well, that's hindsight.