Detect Windows 11 with .NET Framework or Windows API

This most likely isn't perfect, but it's a workaround I've been using for a bit:

Environment.OSVersion.Version.Build >= 22000;

Windows 11 starts at build number 22000 and Windows 10 ends roughly at build number 21390, so this will only detect Windows 11 builds as far as I'm aware.

Do check whether it even is a Windows system in the first place though, another OS might have a higher build number.

RtlGetVersion() gave same results for Windows 10 and 11 as for me. I called it from the C# code as described here https://stackoverflow.com/a/49641055. I tried the Caption property of the WMI's Win32_OperatingSystem class.

using (var objOS = new ManagementObjectSearcher("SELECT * FROM Win32_OperatingSystem"))
{
    foreach (ManagementObject objMgmt in objOS.Get())
    {
        Console.WriteLine("{0}: {1}", objMgmt.Properties["Caption"].Name, objMgmt.Properties["Caption"].Value);
    }
}

For Windows 10 I got "Microsoft Windows 10 Enterprise" and for Windows 11 "Microsoft Windows 11 Pro". Probably you could use the Name property but it contains excessive information like Windows folder and system drive or something like that.

Use this code:

public static bool IsWindows11()
{
    var reg = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\Windows NT\CurrentVersion");

    var currentBuildStr = (string)reg.GetValue("CurrentBuild");
    var currentBuild = int.Parse(currentBuildStr);

    return currentBuild >= 22000;
}

This is based on my findings on HKLM\Software\Microsoft\Windows NT\CurrentVersion: What's the difference between CurrentBuild and CurrentBuildNumber?

And note that this code can throw exceptions in case that the registry key does not exist or in case the value is not number. This should not happen in a normal system. But if you want to be safe, you can warp it in a try-catch block.

You can use RtlGetVersion() in ntdll.dll, which is not subject to OS compatibility manifestation, like GetVersion/Ex() and other similar APIs are (and especially since there is no supportedOS GUID defined for Windows 11 yet).

Windows 10 start with build 10240 and end with build 19044
Windows 11 start with build 22000

Source