How to read from Registry under LOCAL_MACHINE

Question

I am prepairing an Windows form application which will show the Bitness of currently installed office(2016). I have placed a Button(ChkBtn) and a Label(BitnessLbl) in my form, that will help to accomplish my task. The problem is that even though I can find the value of the 'Bitness'('x64' in my case) by searching in the registary, the program fails to locate the specified registary. I have added an image that will further explain my problem. And the code that I am using is as follows

using System;
using System.Windows.Forms;
using Microsoft.Win32;

namespace GetOfficeBitness
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void ChkBtn_Click(object sender, EventArgs e)
        {
            var arg = @"SOFTWARE\Microsoft\Office\16.0\Outlook";
            var key = Registry.LocalMachine.OpenSubKey(arg, false);//OpenSubKey(arg);
            /*var p = Registry.LocalMachine.GetSubKeyNames();
            var l = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\Office\16.0\Common");
            var n = l.GetSubKeyNames();*/
            if (key != null)
            {
                if (key.GetValue("Bitness").ToString() == "x86" || key.GetValue("Bitness").ToString() == "X86")
                    BitnessLbl.Text = @"32 Bit Office";
                //Environment.Exit(1);
            }
            else
            {
                //Environment.Exit(0);
                BitnessLbl.Text = @"64 Bit Office";
            }

        }
    }
}

Image link goes here:- https://i.sstatic.net/XUcuX.png

Answer 1

As I indicated in a comment, when your code is running as a 32-bit process, you're experiencing the effects of the Registry Redirector.

When it looks like your code is accessing HKEY_LOCAL_MACHINE\Software, it is in fact accessing HKEY_LOCAL_MACHINE\Software\Wow6432Node.

To counter the effects, make sure you open your key using an appropriate method/overload that accepts a RegistryView and request the 64-bit view. E.g. you may need to use OpenBaseKey rather than using the built-in LocalMachine property as your starting point.

So, something along the lines of:

var key = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine
                                 ,RegistryView.Registry64).OpenSubKey(arg, false);