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Editorial Team
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Asked: 2026-06-01T14:59:28+00:00

My user is an Administrator (I see it in the configuration panel), the below

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My user is an Administrator (I see it in the configuration panel), the below code throws a Win32Exception in which it says Access Denied, how can I change this (Win7 32 bits) ?

static Guid VideoGuid = new Guid("4d36e968-e325-11ce-bfc1-08002be10318");

[SecurityPermission(SecurityAction.Demand, UnmanagedCode = true)]
static void Main(string[] args)
{
    SafeDeviceHandle handle = null;
    try
    {
        handle = NativeMethods.SetupDiGetClassDevs(ref VideoGuid, IntPtr.Zero, IntPtr.Zero, NativeMethods.DIGCF.PRESENT);
        var data = new NativeMethods.SP_DEVINFO_DATA().Initialize();
        var param = new NativeMethods.SP_PROPCHANGE_PARAMS().Initialize();
        param.ClassInstallHeader.InstallFunction = 0x12;
        param.StateChange = NativeMethods.DICS.ENABLE; // 0x01
        param.Scope = NativeMethods.DICS_GLOBAL.GLOBAL; // 0x01
        param.HwProfile = 0;

        RunWin32Method(() => NativeMethods.SetupDiEnumDeviceInfo(handle, 0u, out data));
        RunWin32Method(() => NativeMethods.SetupDiSetClassInstallParams(handle, ref data, ref param, (UInt32)Marshal.SizeOf(param)));
        RunWin32Method(() => NativeMethods.SetupDiChangeState(handle, ref data));
    }
    catch
    {
        var w = new Win32Exception(Marshal.GetLastWin32Error());
    }
    finally
    {
        if (handle != null && (!handle.IsInvalid))
            handle.Close();
    }
}

static void RunWin32Method(Func<bool> f)
{
    if (!f())
    {
        Debug.WriteLine(new Win32Exception(Marshal.GetLastWin32Error()).Message);
    }
}

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1 Answer

  1. Editorial Team

    Recapping the comment trail, a user in the Administrator group doesn’t have admin rights on Vista/Server 2008 and later unless the process runs elevated. A manifest is required to get Windows to display the UAC elevation prompt.

    This cannot work for programs that are started at login by the Run registry key or the Startup folder. Windows refuses to display the elevation prompt because the user cannot accurately guess exactly what program asked for the elevation. Code-signing the program with a certificate may fix this since that permits Windows to verify and display the program owner, never actually tried that.

    Workarounds for such programs are activating it as a service or a scheduled task. Neither of which requires the manifest. The theory behind this seeming oddity is that it already requires elevation to get a service or scheduled task installed.

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