I was trying to develop a shell extension via SharpShell in windows 11
Firstly, following the demo “CountLines” in this guide: https://www.codeproject.com/Articles/512956/NET-Shell-Extensions-Shell-Context-Menus,
I copied the code and build it in Release mode, everything works fine by now.

Then, I tried several methods to deploy the generated dll, such as regasm, srm or ServerManager, each method works. However, the Context Menu for txt files doesn’t have a “CountLines” item. By the way, it works fine in ServerManager.exe test shell.

Then, I used ShellexView to check my extension, it do existed. But its file path shows:
“C:WindowsSystem32D:/my/custom/path/shellext.dll”

Why did it happen?

Here comes my code and some results:

using System.IO;
using System.Runtime.InteropServices;

using System.Text;

using SharpShell;
using SharpShell.SharpContextMenu;
using SharpShell.Attributes;

using System.Windows.Forms;

/// <summary>
/// The CountLinesExtensions is an example shell context menu extension,
/// implemented with SharpShell. It adds the command 'Count Lines' to text
/// files.
/// </summary>
[ComVisible(true)]
[COMServerAssociation(AssociationType.ClassOfExtension, ".txt")]
public class CountLinesExtension : SharpContextMenu
{
    /// <summary>
    /// Determines whether this instance can a shell
    /// context show menu, given the specified selected file list
    /// </summary>
    /// <returns>
    /// <c>true</c> if this instance should show a shell context
    /// menu for the specified file list; otherwise, <c>false</c>
    /// </returns>
    protected override bool CanShowMenu()
    {
        //  We always show the menu
        return true;
    }

    /// <summary>
    /// Creates the context menu. This can be a single menu item or a tree of them.
    /// </summary>
    /// <returns>
    /// The context menu for the shell context menu.
    /// </returns>
    protected override ContextMenuStrip CreateMenu()
    {
        //  Create the menu strip
        var menu = new ContextMenuStrip();

        //  Create a 'count lines' item
        var itemCountLines = new ToolStripMenuItem
        {
            Text = "Count Lines...",
        };

        //  When we click, we'll count the lines
        itemCountLines.Click += (sender, args) => CountLines();

        //  Add the item to the context menu.
        menu.Items.Add(itemCountLines);

        //  Return the menu
        return menu;
    }

    /// <summary>
    /// Counts the lines in the selected files
    /// </summary>
    private void CountLines()
    {
        //  Builder for the output
        var builder = new StringBuilder();

        //  Go through each file.
        foreach (var filePath in SelectedItemPaths)
        {
            //  Count the lines
            builder.AppendLine(string.Format("{0} - {1} Lines",
              Path.GetFileName(filePath), File.ReadAllLines(filePath).Length));
        }

        //  Show the output
        MessageBox.Show(builder.ToString());
    }
}

in ServerManager.exe test shell:
enter image description here

Install shellext server in ServerManager.exe:
enter image description here

Weird filename in shellexview:
enter image description here

However, in registry, its path seems right?
enter image description here

I have tried to use srm or regasm to register the dll, both of them show the same result