Develop Reference

Cannot change registry variable C#

I'm in the middle of creating my own kiosk using C#, and for that I'm going to kill explorer (windows shell) and I don't need it to autorestart. For that cause I need to change one variable in the registry however, when I'm trying to run it from the IDE it gives me an error:
System.UnauthorizedAccessException:Access to the registry key %KEYPATH% is denied.
If I try to run the executable as an administrator, I get no error messages but nothing changes, variable is still set to "1".
I also edited the permissions for that branch in registry for current user and even everyone, giving full access to that branch in the registry. This is the C# code I have
RegistryKey explorerAutoRestart;
string ear_keypath = #"SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon";
//GETTING ACCESS ERROR HERE
explorerAutoRestart = Registry.LocalMachine.CreateSubKey(ear_keypath);
switch (status)
{
case "0":
RegistryKey key = Registry.LocalMachine.CreateSubKey(#"Software\Microsoft\Windows NT\CurrentVersion\Winlogon");
key.SetValue("AutoRestartShell", 0x00000000, RegistryValueKind.DWord);
key.Close();
break;
case "1":
explorerAutoRestart.SetValue("AutoRestartShell", 1, RegistryValueKind.DWord);
explorerAutoRestart.Close();
break;
}
I would like to know what's causing this issue and how do I change the value of
AutoRestartShell - REG_DWORD
Changing CreateSUbKey to OpenSubKey(path, true) only changed the error to
Requested registry access is not allowed.
Perhaps Windows doesn't allow external editing for that branch?

Managed to solve this issue. Apparently my keys were redirected by WOW64 and that somehow didn't give me permission to the registry branch?
Nonetheless following code saved me:
RegistryKey localMachine = RegistryKey.OpenBaseKey(Microsoft.Win32.RegistryHive.LocalMachine, RegistryView.Registry64);
RegistryKey regKey = localMachine.OpenSubKey(#"SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon", true);
regKey.SetValue("Shell", "bat.exe", RegistryValueKind.String);
regKey.Close();
Changing the Shell registry

CreateSubKey is not creating entry in current user

I am trying to create a sub key under Current user, Application runs successfully, but unable to create sub key under current user. Following is my application logic. Can any one tell me what mistake I am doing here?
RegistryKey myAppSettings = Registry.CurrentUser.CreateSubKey(#"SOFTWARE\MyAppSettings");
Console.WriteLine(myAppSettings);
//storing the values
myAppSettings.SetValue("appName", "C# Tutorials");
myAppSettings.SetValue("Demo", "Registry keys storage");
myAppSettings.Close();

CreateSubkey does not work with path values. You have to open the RegistryKey "software" and create the subkey for it.

How to get The Child Folder Name of HKEY_USERS in C#?

Im Trying to get the installed applications in this registry entry.
HKEY_USERS\S-1-5-21-xxxxxx-xxxxxx-xxxxxx-1000\SOFTWARE\Microsoft\Win‌​dows\CurrentVersion\Uninstall
The below code works, if you replace the registry_Key's First part (where the x's are) with your folder name. But how can i get that folder name so that i can use this code on any computer, since that folder name is different on each pc?
In other words, how will i get this part of the string S-1-5-21-xxxxxx-xxxxxx-xxxxxx-1000
registry_key = #"> HKEY_USERS\S-1-5-21-xxxxxx-xxxxxx-xxxxxx-1000\SOFTWARE\Microsoft\Win‌​dows\CurrentVersion\Uninstall";
using (Microsoft.Win32.RegistryKey key = Registry.LocalMachine.OpenSubKey(registry_key))
{
foreach (string subkey_name in key.GetSubKeyNames())
{
using (RegistryKey subkey = key.OpenSubKey(subkey_name))
{
textBox2.Text += subkey.GetValue("DisplayName") + "\r\n";
}
}
}

If you want a list of the USER profiles availabe to traverse the registry on the HKEY_USERS registry hive you could read and filter the contents of
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList
However, you need to have permissions to open the registry hive of an user different from the current user (Administrator I think, never done).
If you need only to check the CURRENT_USER registry, it 's easier to use directly the key
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Win‌​dows\CurrentVersion\Uninstall

Finding Registry Keys in C#

I am working on a project that will allow me to delete the registry key from a Windows 7 PC. Specifically I am trying to make a program that will allow me to delete a profile from the machine via the ProfileList key. My problem is no matter what I try I can't seem to read the key correctly which I want to do before I start randomly deleting stuff. My code is
RegistryKey OurKey = Registry.LocalMachine;
OurKey = OurKey.OpenSubKey(#"SOFTWARE\Microsoft\WindowsNT\CurrentVersion\ProfileList", true);
foreach (string Keyname in OurKey.GetSubKeyNames())
{
MessageBox.Show(Keyname);
}
This code runs but doesn't return anything (No MessageBox). Any ideas why not?
EDIT:
I got the top level keys to load thanks to you all but it does only show the folder/key names (Ex: S-1-5-21-3794573037-2687555854-1483818651-11661) what I need is to read the keys under that folder to see what the ProfilePath is. Would there be a better way to go about that?

As pointed out by Lloyd, your path should use "Windows NT". In case of doubt, always use regedit to go inspect the registry manually.
Edit: To go with your edit, you can simply GetValue on the keys you find, the following code should do what you're looking for:
RegistryKey OurKey = Registry.LocalMachine;
OurKey = OurKey.OpenSubKey(#"SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList", true);
foreach (string Keyname in OurKey.GetSubKeyNames())
{
RegistryKey key = OurKey.OpenSubKey(Keyname);
MessageBox.Show(key.GetValue("KEY_NAME").ToString()); // Replace KEY_NAME with what you're looking for
}

Windows NT
Please do not miss space

Writing to registry in a C# application

I'm trying to write to the registry using my C# app.
I'm using the answer given here: Writing values to the registry with C#
However for some reason the key isn't added to the registry.
I'm using the following code:
string Timestamp = DateTime.Now.ToString("dd-MM-yyyy");
string key = "HKEY_LOCAL_MACHINE\\SOFTWARE\\"+Application.ProductName+"\\"+Application.ProductVersion;
string valueName = "Trial Period";
Microsoft.Win32.Registry.SetValue(key, valueName, Timestamp, Microsoft.Win32.RegistryValueKind.String);
The Application.name and Application.version 'folders' don't exists yet.
Do I have to create them first?
Also, I'm testing it on a 64b Win version so I think if I want to check the registry for the key added I have to specifically check the 32bit registry in: C:\Windows\SysWOW64\regedit.exe don't I?

First of all if you want to edit key under LocalMachine you must run your application under admin rights (better use CurrentUser it's safer or create the key in installer). You have to open key in edit mode too (OpenSubKey method) to add new subkeys. I've checked the code and it works. Here is the code.
RegistryKey key = Registry.LocalMachine.OpenSubKey("Software",true);
key.CreateSubKey("AppName");
key = key.OpenSubKey("AppName", true);
key.CreateSubKey("AppVersion");
key = key.OpenSubKey("AppVersion", true);
key.SetValue("yourkey", "yourvalue");

You can use the following code to create and open the required registry keys.
RegistryKey SoftwareKey = Registry.LocalMachine.OpenSubKey("Software",true);
RegistryKey AppNameKey = SoftwareKey.CreateSubKey("AppName");
RegistryKey AppVersionKey = AppNameKey.CreateSubKey("AppVersion");
AppVersionKey.SetValue("yourkey", "yourvalue");
You can basically use CreateSubKey for all your application settings, as it will open the key for write access, if it already exists, and create it otherwise. There is no need to create first, and then open. OpenSubKey comes in handy when you are absolutely certain the key already exists, like in this case, with "HKEY_LOCAL_MACHINE\SOFTWARE\"

Also check if your registry calls are getting virtualised. See here for more information.
It can happen if your application is not UAC aware and occurs for compatibility reasons.
Real path
HKEY_LOCAL_MACHINE\Software\FooKey
Virtual path
HKEY_USERS\<User SID>_Classes\VirtualStore\Machine\Software\FooKey

Try to open HKLM\Software first. Then create key for your program, and then create key for version. Howewer, your key could be placed at HKLM\software\WOW6432Node. Check this.

The problem is you don't have enough privileges. Here is a way that works for my:
RegistryKey myKey = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry64);
myKey = myKey.OpenSubKey(subkey, RegistryKeyPermissionCheck.ReadWriteSubTree, RegistryRights.FullControl);
if (myKey != null)
{
myKey.SetValue("DefaultPrinterId", ldiPrinters[e.RowIndex].id, RegistryValueKind.String);
myKey.Close();
}
With RegistryKey.OpenBaseKey you open the correct registry, because when you don't have permissions the registry that you write, it does in another location.

By default, your changes will be written to HKLM\SOFTWARE\WOW6432Node\... because of registry redirection. This can be quite confusing.
In order to write to HKLM\SOFTWARE\..., you need to use RegistryKey.OpenBaseKey to open the 64-bit registry:
var path = #"SOFTWARE\...";
var baseKey = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry64);
var key = baseKey.CreateSubKey(path, RegistryKeyPermissionCheck.ReadWriteSubTree);
key.SetValue(name, value, RegistryValueKind.String);
Also, you need to have permission to write to the specified registry key.
You can get permission either by assigning permissions to specific users or service accounts or by running your app in elevated mode.