It's complaining there's NO ST-LINK
Does it show up in Device Manager?
Do you have it open in any other application?
Is this a stand-alone ST-LINK, authentic? or on a NUCLEO or DISCO board?
Try a different cable.
Make sure any application or window, for the tools or the upgrade app are closed.
Try on a different machine.
Try the stand-alone upgrade application.
Try with it disconnected from the Target MCU
