c# – Windows Installer with CustomInstaller and Error 1001. Unable to get installer types in the dll assembly

My solution has 3 projects with a project for CustomInstaller, a project for my WPF app and my Setup Installer.

After building my setup installer and running it, in the middle of the process I do have the error message:

Error 1001. Unable to get installer types in the C:\Miopro\MS4\Miopro.Setup.Prerequisites.dll assembly. –> Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.

Here is my Visual Studio 2022 Solution:

• Miopro.Setup.Prerequisites
  • Class Library
  • .Net 7.0
  • Platform Target x86
• Miopro.Suite.Wpf
  • WPF Windows Application
  • .Net 7.0
  • Platform Target x86
• Miopro.Setup
  • Windows Installer Setup Project
  • Configuration Active (Debug)
  • Configuration Manager has al projects with Platform Any CPU
  • File System on Target Machine
    • Application Folder Default Location: C:[Manufacturer]\MS4
    • Application Folder
      • Primary output from Miopro.Setup.Prerequisites
      • Publish Items from Miopro.Setup.Prerequisites
      • Publish Items from Miopro.Suite.Wpf
  • Custom Actions
    • Install
      • Primary output from Miopro.Setup.Prerequisites

Environment:

File System

Custom Action

CustomInstaller class

using System;
using System.ComponentModel;
using System.Configuration.Install;
using System.Diagnostics;
using System.IO;

namespace Miopro.Setup.Prerequisites
{
    [RunInstaller(true)]
    public class CustomInstaller : Installer
    {
        public CustomInstaller() : base()
        {
            this.Committed += new InstallEventHandler(CustomInstaller_Committed);
            this.Committing += new InstallEventHandler(CustomInstaller_Committing);
        }

        public static void Main()
        {
            WriteToEventLog("Install");
        }

        /// <summary>
        /// Event handler for 'Committing' event.
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void CustomInstaller_Committing(object sender, InstallEventArgs e)
        {
            WriteToEventLog("Committing Event occurred.");
        }

        /// <summary>
        /// Event handler for 'Committed' event.
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void CustomInstaller_Committed(object sender, InstallEventArgs e)
        {
            WriteToEventLog("Committed Event occurred.");
        }

        public override void Install(System.Collections.IDictionary stateSaver)
        {
            base.Install(stateSaver);
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="savedState"></param>
        public override void Commit(System.Collections.IDictionary savedState)
        {
            base.Commit(savedState);
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="savedState"></param>
        public override void Rollback(System.Collections.IDictionary savedState)
        {
            base.Rollback(savedState);
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="savedState"></param>
        public override void Uninstall(System.Collections.IDictionary savedState)
        {
            base.Uninstall(savedState);
        }

        private static void WriteToEventLog(string message)
        {
            string source = "Miopro.Setup.Prerequisites.CustomInstaller";
            string log = "Application";

            if (!EventLog.SourceExists(source))
            {
                EventLog.CreateEventSource(source, log);
            }

            EventLog.WriteEntry(source, message, EventLogEntryType.Information);
        }
    }
}

So, when I’m installing I can see my Miopro.Setup.Prerequisites.dll on my Application Folder Default Location, so it is available.

I already ready a few of the post over here, but none of them are talking about CustomInstaller on Custom Actions. What´s is the possible reason to get this error message?