:Go to Start > Settings > Update & Security > Activation . Windows 10 and 11 have built-in troubleshooters that replace the old standalone tools.

If you need to diagnose activation issues on a modern OS, stop using the MGA Diagnostic Tool and try these instead:

This diagnostic tool was originally designed to verify licenses for legacy systems like . Because Microsoft has shifted to newer activation technologies, this specific tool is no longer compatible with modern versions like Windows 10 or 11. Why You're Seeing This Error

: On older systems, the tool sometimes fails if you aren't using Internet Explorer with the correct ActiveX plugins enabled. How to Fix or Bypass the Error

: Microsoft officially retired many components of the Windows Genuine Advantage (WGA) system years ago in favor of integrated digital licensing.

: The tool (MGADiag.exe) is generally for Windows 7 or older. Running it on Windows 8, 10, or 11 will trigger the "unsupported OS" message.