If you paid extra for Windows 10 "Pro," Microsoft had an unpleasant surprise for you: a misconfiguration in the company's license server resulted in the oldest Win 10 Pro installs (that is, those owned by Microsoft's earliest adopting customers) being downgraded to Windows 10 Home, with users' screens plastered with watermarks chiding them for not paying for their licenses (this went over great for everyone who was standing in front of an audience giving a presentation, apparently).
After a period of initial confusion, Microsoft finally admitted something was broken.
