Registry.LocalMachine.OpenSubKey() returns null

Question

I get a null back from this attempt to access the Windows Registry:

using (RegistryKey registry = Registry.LocalMachine.OpenSubKey(keyPath))

keyPath is SOFTWARE\\TestKey

The key is in the registry, so why is it not finding it under the Local Machine hive?

Are you properly escaping KeyPath? Is it "SOFTWARE\\TestKey", and not "SOFTWARE\TestKey"? — Michael, Aug 12 '09 at 21:05
So this has worked on my boss's PC just fine. No reason why it should not here. I gave asp.net account access to it since I'm running the VS web server and still returns null. — PositiveGuy, Aug 12 '09 at 21:11

score 66 · Answer 1 · edited Feb 13 '15 at 02:23

66

It can happen if you are on a 64-bit machine. Create a helper class first (requires .NET 4.0 or later):

public class RegistryHelpers
{

    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);
    }
}

Usage:

string keyPath = @"SOFTWARE\MyApp\Settings";
string keyName = "MyAppConnectionStringKey";

object connectionString = RegistryHelpers.GetRegistryValue(keyPath, keyName);

Console.WriteLine(connectionString);
Console.ReadLine();

edited Feb 13 '15 at 02:23

Peter Mortensen

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answered Nov 02 '12 at 06:07

Raghav

8,772
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10

It should be noted that this answer requires .NET 4.0 or higher. – ganders Nov 05 '12 at 16:13
5

On 64-bit Windows there is two regedit utilities. C:\Windows\System32\regedt32.exe and C:\Windows\SysWOW64\regedt32.exe. Each one gives you a different RegistryView – Marco M. Aug 27 '13 at 15:53
2

Is there any way to do this in .NET 3.5? – Mike Hanson Mar 20 '14 at 20:58
Thanks. Saved my time. – The King Sep 23 '15 at 07:05
3

The 64-bit check isn't required. From MSDN: `If you request a 64-bit view on a 32-bit operating system, the returned keys will be in the 32-bit view.` – brettwhiteman Nov 08 '15 at 05:00

score 2 · Accepted Answer · edited Feb 13 '15 at 02:21

2

In your comment to Dana you said you gave the ASP.NET account access. However, did you verify that that is the account that the site in running under? Impersonate and the anonymous access user can be easy to overlook.

UNTESTED CODE:

Response.Clear();  
Response.Write(Environment.UserDomainName + "\\" + Environment.UserName);  
Response.End();

edited Feb 13 '15 at 02:21

Peter Mortensen

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105
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answered Aug 12 '09 at 21:21

KellCOMnet

1,859
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How can I figure out which account the site is running under without having to write code to expose? – PositiveGuy Aug 12 '09 at 21:29
well the above is generally how i troubleshoot account issues although i do add a check in that it is coming from my ip address so that not just everyone can see it. – KellCOMnet Aug 14 '09 at 12:19

score 1 · Answer 3 · answered Nov 14 '18 at 19:18

1

Just needed to change it from

using (RegistryKey registry = Registry.LocalMachine.OpenSubKey(keyPath))

to

using (RegistryKey registry = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Default).OpenSubKey(keyPath))

(Use RegistryKey instead of Registry , add the RegistryView, and put the hive-Local Machine as a method parameter.)

answered Nov 14 '18 at 19:18

vapcguy

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RegistryView.Default didn't work for me, I used what was specified in the most popular answer (but I like this answer's conciseness): Environment.Is64BitOperatingSystem ? RegistryView.Registry64 : RegistryView.Registry32 – Ronny D'Hoore Oct 13 '22 at 12:17
Yeah, I think when you're going between 32-bit & 64-bit it makes a difference, so you have to specify which one. So adding that in, in place of `RegistryView.Default`, is a good idea. – vapcguy Oct 21 '22 at 18:11

Registry.LocalMachine.OpenSubKey() returns null

3 Answers3

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