Registry key deleted but still getting value from registry c#

Question

I created windows application. When i am creating registry value through code its working well but after deleting from registry (i am deleting that registry using regedit from cmd). Still showing that value in my code when i am debugging from visual studio.

My code for registry creation

RegistryKey key = Registry.LocalMachine.CreateSubKey(@"SOFTWARE\TOPO");
if (key != null)
{
   //key.SetValue("interval", "5000");
   key.SetValue("Topos", 1, RegistryValueKind.DWord);
   key.Close();
}

then i am checking value from Program.cs

string strval = string.Empty;
RegistryKey key = Registry.LocalMachine.CreateSubKey(@"SOFTWARE\TOPO");
if (key != null)
{
   //key.SetValue("interval", "5000");
   bb = Convert.ToInt32(key.GetValue("Topos"));
   key.Close();
}

Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);

if (bb == 1)
{ 
    Application.Run(new frm_mdi());
}
else
{
    Application.Run(new frm_activation());
}

Looks like you're creating the key every time you run the program, so it would make sense that it is there even after deleting it manually and running again. — mjw, Jun 09 '17 at 13:06
_What_ value is shown? You do a `CreateSubKey`, which creates the _key_ everytime anew. And `GetValue` does not throw an exception if the _value_ does not exist, but returns `null`, which is converted to `0` by `Convert.ToInt32()`. — René Vogt, Jun 09 '17 at 13:08
If your program is running as 32-bit process on 64-bit OS, your program may actually read value from `HKLM\Software\WOW6432Node\TOPO` instead of `HKLM\Software\TOPO` because read from registry is redirected by WOW64 layer - see [How to view the system registry by using 64-bit versions of Windows](https://support.microsoft.com/en-us/help/305097/how-to-view-the-system-registry-by-using-64-bit-versions-of-windows) — Ňuf, Jun 09 '17 at 13:50
@Ňuf Yes , You are correct its storing key into wow64, Please tell what changes i have to make in my code now ? — Nitin Patil, Jun 10 '17 at 03:18

score 2 · Accepted Answer · answered Jun 10 '17 at 14:40

In Windows XP and newer, certain registry keys are either redirected, reflected or shared between 32-bit and 64-bit processes. Particularly HKLM\Software\TOPO should be redirected to HKLM\Software\WOW6432Node\TOPO, according to this article. More on redirection here. Therefore when you delete key from registry using Regedit (which is 64-bit), 32-bit version of the key still remains in registry.

SOLUTION

Option 1

If possible, let your application run as 64-bit process on 64-bit Windows. Assuming you are using Visual Studio and your application targets Any CPU solution platform, you can do this by right-click on project -> Properties -> Build tab and unchecking "Prefer 32-bit" checkbox for all desired configurations.

Option 2

Modify your program, to access 64-bit version of registry even if it is running as 32-bit process. You can do this with something like this:

var key = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry64)
    .OpenSubKey(@"SOFTWARE\TOPO");

See this answer if you need more details.

Option 3

When deleting/modifying/creating registry using regedit, simply edit HKLM\Software\WOW6432Node\TOPO key instead of HKLM\Software\TOPO.

score 0 · Answer 2 · answered Mar 29 '19 at 08:12

I had a similar problem and in my case I found there is one more kind of registry keys redirect for VSTO based Office Add-ins. If you use new Click-to-run installation of Office and save/read registry keys from within an Office Add-in it might be redirected to another location like: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\ClickToRun\REGISTRY\MACHINE\Software\TOPO

Registry key deleted but still getting value from registry c#

2 Answers2

SOLUTION

Linked

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