How to reliably check whether Windows Update is enabled using C#?

Question

I tried to check if Windows Update is enabled. I added a reference to c:\windows\system32\wuapi.dll on Windows 7 x64 Ultimate and wrote this code

using WUApiLib;
public Boolean IsWindowsUpdateEnabled()
{
    var updates = new AutomaticUpdatesClass();
    return updates.ServiceEnabled;
}

The code fails to build. I get the following error:

Error 1 The type 'WUApiLib.AutomaticUpdatesClass' has no constructors defined
Error 2 Interop type 'WUApiLib.AutomaticUpdatesClass' cannot be embedded. Use the applicable interface instead.
Error 3 'WUApiLib.AutomaticUpdatesClass' does not contain a definition for 'ServiceEnabled' and no extension method 'ServiceEnabled' accepting a first argument of type 'WUApiLib.AutomaticUpdatesClass' could be found (are you missing a using directive or an assembly reference?)

Answer 1

In your Visual Studio project References list, find the WUApiLib reference and change its "Embed Interop Types" to "False".