Question

I’m getting a NullReferenceException error on some simple code for handling a button click event. I’ve still got just a bit of code to add at the very end to actually display the value from “TcpAddr” on the messagebox. This will allow you run the program but clicking the button causes it to throw the error.

Also: Is it better practice to move the actual query out of the click event and just make the click event handle MessageBox.Show()?

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

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

        private void button2_Click(object sender, EventArgs e)
        {
            RegistryKey RegKey = Registry.LocalMachine;
            RegKey = RegKey.OpenSubKey("SOFTWARE\\Altiris\\Client Service");
            object CurrDS = RegKey.GetValue("TcpAddr"); //This line causes the NRE Error
            MessageBox.Show("Current DS:");
        }
    }
}

Answer 1

If you are sure that the registry key actually exists (use Regedit.exe) then you’ve got a problem if you are running on the 64-bit version of Windows. A VS2010 project is forced to run in 32-bit mode by default, it sees another set of registry keys.

Project + Properties, Build tab, Platform Target = Any CPU. Repeat for the Release configuration.