https://www.computerworld.com/article/3319737/microsoft-windows/win10-activation-server-down-your-pro-license-is-still-good-despite-the-warnings.html [computerworld.com]:
A bug in Microsoft’s activation server has led to pandemonium among people trying to activate or re-activate their Windows 10 Pro licenses. No need to panic. Microsoft will fix it “within one to two business days.” (Try telling your boss that.)
If you see a bogus report about an invalid Win10 Pro license, relax. It’s just Microsoft’s servers screwing up, again, and everything should be copacetic in a couple of days.
On Twitter, Windows leaker emeritus Faikee posted this screenshot [twitter.com]:
[...] There’s also a lengthy diatribe [reddit.com] on Reddit.
[...] The only breath of hope that I’ve found comes from the Microsoft Answers Forum, where Daniel Randy quotes a Live Agent response as saying:
Thank you for sharing, Daniel. Microsoft has just released an Emerging issue announcement about current activation issue related to Pro edition recently. This happens in Japan, Korea, American and many other countries. I am very sorry to inform you that there is a temporary issue with Microsoft's activation server at the moment and some customers might experience this issue where Windows is displayed as not activated.
Our engineers are working tirelessly to resolve this issue and it is expected to be corrected within one to two business days, Daniel.