It sounds like your plugin is named ‘Toolbox’ and in that plugin you have a module that is also named ‘Toolbox’, is that correct? If so, there may be something wrong with how you’ve defined the module class.
Your code module ‘Toolbox’ needs to be defined in Toolbox.Build.cs in a way that looks like this:
using UnrealBuildTool;
using System;
using System.IO;
public class Toolbox : ModuleRules
{
public Toolbox(ReadOnlyTargetRules Target) : base(Target)
{
// Module settings and dependencies go in here - see
// https://docs.unrealengine.com/5.0/en-US/unreal-engine-modules/
}
}
You also need a C++ class in your module that is associated with the Toolbox C# class. You (probably) want that to be called FToolboxModule, and add it in ToolboxModule.h / ToolboxModule.cpp. It should inherit from IModuleInterface. It gets associated with the C# class, by including the following macro in ToolboxModule.cpp:
IMPLEMENT_MODULE(FToolboxModule, Toolbox)