C# Registry SetValue throws UnauthorizedAccessException

Question

Before you try to answer this with, "Do a quick Google search." I'd like to point out that I have already. Here is the situation, I have the following method that attempts to modify a registry key value. The problem I'm getting is that when executed, it throws an UnauthorizedAccessException even though I've opened the key as writeable. I'm running Visual Studio as administrator and even tried to make a small .exe with a manifest file forcing it to run as admin that will execute the code with no luck. The key already exists, it doesn't try to go into the CreateKey method. Here is the block of code.

Path = "S-1-5-21-1644491937-1078145449-682003330-5490\Software\Microsoft\Windows\CurrentVersion\Policies\System"
Key = "DisableTaskMgr"
NewValue = 1

public OperationResult ModifyKey()
    {
        OperationResult result = new OperationResult();

        if (!Path.IsNullOrEmptyTrim())
        {
            if (!Key.IsNullOrEmptyTrim())
            {
                try
                {
                    var key = Microsoft.Win32.Registry.Users.OpenSubKey(Path, true);

                    if (key != null)
                    {
                        key.SetValue(Key, NewValue);

                        key.Close();
                    }
                    else
                    {
                        result = CreateKey();
                    }
                }
                catch (Exception ex)
                {
                    result.SetFail("Error accessing registry", ex);
                }
            }
            else
            {
                result.SetFail("Registry key was null");
            }
        }
        else
        {
            result.SetFail("Registry path was null");
        }

        return result;
    }

Do I have to manually walk down the registry tree setting each OpenSubKey call to writeable? I tried this as well, still threw the same error...

Answer 1

in the var for your key

var key = Microsoft.Win32.Registry.Users.OpenSubKey(Path, true);

change to

var key = Microsoft.Win32.Registry.Users.OpenSubKey(Path, RegistryKeyPermissionCheck.ReadWriteSubTree);  

Answer 2

I ran into the same problem recently. So I tried a few things and instead of calling key.SetValue(Key, NewValue) simply calling create function solved my problem. That is;

Microsoft.Win32.RegistryKey key1 = Microsoft.Win32.Registry.Users.CreateSubKey(Path);
key1.SetValue(Key, NewValue);

CreateSubKey call doesn't delete the current entry but provided with the ability to write without exception. I hope that helps.

Answer 3

Have you tried setting the accessrule and permissions?

 string user = Environment.UserDomainName + "\\" + Environment.UserName;
 RegistryAccessRule rule = new RegistryAccessRule(user,
        RegistryRights.FullControl,
        AccessControlType.Allow);        
 RegistrySecurity security = new RegistrySecurity();
 security.AddAccessRule(rule);
 var key = Microsoft.Win32.Registry.Users.OpenSubKey(subKeyPath, RegistryKeyPermissionCheck.ReadWriteSubTree, RegistryRights.FullControl);
 key.SetAccessControl(security);