Reading registry value crashes

Question

My below code fails no matter if I run it as Administrator or not:

var suff = Registry.LocalMachine.OpenSubKey("Software\\Microsoft\\CCM\\LocationServices", true);
var value = suff.GetValue("DnsSuffix").ToString();

I get this error message which I can't decode:

An unhandled exception of type 'System.NullReferenceException' occurred in MyApp.exe Additional information: Object reference not set to an instance of an object.

I know for a fact that the value exists and it contains data as well.

*Edit: So like I said it shouldn't be null as the data exists. And if it is null then I will need to know why is it null. Therefore, a question regarding what is System.NullReferenceException won't help me at all.

Possible duplicate of [What is a NullReferenceException and how do I fix it?](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — Dmitry, Jan 13 '16 at 15:27
@Dmitry Like I said it is not null. Or if it is then I don't know why. So I believe the question is valid. — fishmong3r, Jan 13 '16 at 15:28
*I know for a fact that the value exists and it contains data as well.* How do you know that? Have you considered it could be an x86 key while your .NET app runs on the x64 CLR (or the other way around)? — Frédéric Hamidi, Jan 13 '16 at 15:30
I'm not aware of any other reasons why the value would be null other than it doesn't exist, you don't have permission or you're looking in the "wrong" registry (x86/x64). [This post](http://stackoverflow.com/questions/13337577/setvalue-64bit-machine-registry) has a good example of making sure your registry code runs on both types of machine, the other two should be obvious to check. — Equalsk, Jan 13 '16 at 15:39

score 3 · Accepted Answer · edited May 23 '17 at 10:28

As raj's answer pointed out in this SO question, which is similar to yours, the problem could be that you're opening the registry on a 64bits OS.

Try this approach instead (.NET 4.0 or later) :

public class HKLMRegistryHelper
{

    public static RegistryKey GetRegistryKey()
    {
        return GetRegistryKey(null);
    }

    public static RegistryKey GetRegistryKey(string keyPath)
    {
        RegistryKey localMachineRegistry = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, Environment.Is64BitOperatingSystem ? RegistryView.Registry64 : RegistryView.Registry32);

        return string.IsNullOrEmpty(keyPath) ? localMachineRegistry : localMachineRegistry.OpenSubKey(keyPath);
    }

    public static object GetRegistryValue(string keyPath, string keyName)
    {
        RegistryKey registry = GetRegistryKey(keyPath);
        return registry.GetValue(keyName);
    }
}

... and replace your code with :

string keyPath = @"SOFTWARE\Microsoft\CCM\LocationServices";
string keyName = "DnsSuffix";

var value = HKLMRegistryHelper.GetRegistryValue(keyPath, keyName);

Link only answers are generally frowned upon, even if it links to another thread. Can you please include the relevant parts of the code in your post with credit to the author? — Equalsk, Jan 13 '16 at 15:43

Seritin · Answer 2 · 2016-01-13T16:21:12.460

Reading the registry with "Registry.LocalMachine" can be unreliable as it defaults to the current application platform target (x86/x64) and when it's 64bit Registry.LocalMachine can view the key but can't access the data within.

Try specifying the view with RegistryKey.

var stuff = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry64)
                .OpenSubKey("Software\\Microsoft\\CCM\\LocationServices", true);
var value = stuff.GetValue("DnsSuffix").ToString();

Reading registry value crashes

2 Answers2