Regasm /codebase for an installer project

OK, so you've spent ages making a little Browser Helper Object (BHO) for Internet Explorer, and you've tested it on many other machines by registering it using regasm like so:

regasm /codebase your.dll

So then you decide the time's right to bundle your code into an installer for mass consumption. You now spend then next week trying to work out how to get your dll registered on the target machine before you go nuts or rip too much of your hair out. Welcome to my world.

I followed countless articles on the web which informed me of the basic pitfalls when trying to register a .NET dll on the target machine using a Visual Studio setup project. These included:

Still nothing. Nowt.

So in the end I got fed up and just created a custom action which will locate regasm in the latest version of the .NET framework that is installed on the target machine and run it against the newly installed dll. Hurrah! It works perfectly!

Realising that I couldn't be the only person who's having this problem, I've decided to share the code to assist others. All you need to do is follow the below steps:

  1. In your main project (the one containing the class you want to register), right click the project file and select Add / New Item and select Installer Class. Call it something like clsRegisterDll.cs
  2. In the designer that appears, click 'Click here to switch to code view' or right click the clsRegisterDll.cs file in solution explorer and select View Code
  3. Replace the code in the window with the code listed below, and make sure you change 'YourNamespace'. This has to match with the namespace in the clsRegisterDll.Designer.cs file.
  4. Compile your project
  5. In your installer, make sure you have added your dll to the Application Folder, and then right-click the installer project and select View / Custom Actions
  6. Right-click Install, and then click Add Custom Action
  7. Double click on Application Folder, and then on your dll
  8. Do the same for the Commit action
  9. Build and test your installer

You should now have an installer that registers your dll using regasm /codebase.


    using System.ComponentModel;
    using System.Configuration.Install;

    namespace YourNamespace
        public partial class RegisterDll : Installer
            public RegisterDll()

            public override void  Commit(System.Collections.IDictionary savedState)

                // Get the location of regasm
                string regasmPath = System.Runtime.InteropServices.RuntimeEnvironment.GetRuntimeDirectory() + @"regasm.exe";
                // Get the location of our DLL
                string componentPath = typeof(RegisterDll).Assembly.Location;
                // Execute regasm
                System.Diagnostics.Process.Start(regasmPath, "/codebase \"" + componentPath + "\"");

            public override void Install(System.Collections.IDictionary stateSaver)