Registry in .NET: DeleteSubKeyTree says the subkey does not exists, but hey, it does!

Question

Trying to delete a subkey tree: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.hdr. .hdr subkey has one subkey, no values. So I use this code:

RegistryKey FileExts = Registry.CurrentUser.CreateSubKey("SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Explorer\\FileExts");
RegistryKey faulty = FileExts.OpenSubKey(".hdr");
Debug.Assert (faulty != null && faulty.SubKeyCount != 0);
faulty.Close();
FileExts.DeleteSubKeyTree(".hdr");

And I get the ArgumentException with message "Cannot delete a subkey tree because the subkey does not exist."

WTF? I checked and asserted it did exist?

Status update

Seeking with Process Monitor, the subkey of ".hdr" gets a ACCESS DENIED error when running the code. I checked the autorizations, but they look fine?

Answer 1

Found a solution, which raises other another question...

After pointing the ACCESS DENIED error with Process Monitor, I just tried to delete subkeys individually:

RegistryKey hdr = FileExts.OpenSubKey(".hdr", true);
foreach (String key in hdr.GetSubKeyNames())
   hdr.DeleteSubKey(key);
hdr.Close();
FileExts.DeleteSubKeyTree(".hdr");

It worked fine, so it's not a permission problem!

For a reason I don't understand, DeleteSubKeyTree needed an empty tree to work.

An explanation, anyone?