Requested registry access is not allowed

I'm writing a tweak utility that modifies some keys under HKEY_CLASSES_ROOT.

All works fine under Windows XP and so on. But I'm getting error Requested registry access is not allowed under Windows 7. Vista and 2008 I guess too.

How should I modify my code to add UAC support?

app.manifest should be like this:

<?xml version="1.0" encoding="utf-8"?>
<asmv1:assembly manifestVersion="1.0" xmlns="urn:schemas-microsoft-com:asm.v1" xmlns:asmv1="urn:schemas-microsoft-com:asm.v1" xmlns:asmv2="urn:schemas-microsoft-com:asm.v2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
   <assemblyIdentity version="1.0.0.0" name="MyApplication.app" />
   <trustInfo xmlns="urn:schemas-microsoft-com:asm.v2">
      <security>
         <requestedPrivileges xmlns="urn:schemas-microsoft-com:asm.v3">
            <requestedExecutionLevel level="requireAdministrator" uiAccess="false" />
         </requestedPrivileges>
      </security>
   </trustInfo>
</asmv1:assembly>

You can't write to the HKCR (or HKLM) hives in Vista and newer versions of Windows unless you have administrative privileges. Therefore, you'll either need to be logged in as an Administrator before you run your utility, give it a manifest that says it requires Administrator level (which will prompt the user for Admin login info), or quit changing things in places that non-Administrators shouldn't be playing. :-)

If you don't need admin privs for the entire app, or only for a few infrequent changes you can do the changes in a new process and launch it using:

Process.StartInfo.UseShellExecute = true;
Process.StartInfo.Verb = "runas";

which will run the process as admin to do whatever you need with the registry, but return to your app with the normal priviledges. This way it doesn't prompt the user with a UAC dialog every time it launches.