Question

I have recently moved to a W7 64bit machine with VS 2010.
My project is set to run on Any CPU. When I change this to be targeted at x86 I noticed some of my registry calls no longer work.

I am trying to read the ProductID field like so:

RegistryKey windowsNTKey = Registry.LocalMachine.OpenSubKey(@"Software\Microsoft\Windows NT\CurrentVersion");
object productID = windowsNTKey.GetValue("ProductId");

productID is always null when running in x86 mode, when running in “Any CPU” it works correctly. What is going on here?

Answer 1

Some registry keys are redirected by WOW64. More information on this topic is available on MSDN
http://msdn.microsoft.com/en-us/library/aa384232(v=vs.85).aspx

If you really want to always access the x64 node (.Net4) :

  RegistryKey localMachine = RegistryKey.OpenBaseKey(Microsoft.Win32.RegistryHive.LocalMachine, RegistryView.Registry64);
  RegistryKey windowsNTKey = localMachine.OpenSubKey(@"Software\Microsoft\Windows NT\CurrentVersion");
  object productID = windowsNTKey.GetValue("ProductId");