Today I found out that my Windows 10 Pro was deactivated. Ran the Activation Troubleshooter and it reported my Windows 10 Pro as Windows 10 Home and I need to purchase a Windows 10 Pro license to reactivate my Windows OS. Was unable to reactivate it through Microsoft Account. Restored computer to Nov 4 2018 and now it is again showing Windows 10 Pro activated. For how long I don't know until Microsoft fixes its Activation Server as per this article: Microsoft is having Activation Server issues right now - gHacks Tech News
Microsoft is having Activation Server issues right now
Reports are coming in from all over the Internet that Windows 10 licenses get revoked on some systems currently and that activation is not available either at the time of writing.
The most common issue that users and administrators experience right now is that the activation status of Windows 10 PCs is changed from activated to not activated. Some users reported that Windows 10 Pro product keys were suddenly turned into Windows 10 Home licenses.
The notification reads:
We found a Windows 10 Home digital license for this device running Windows 10 Pro. To activate using this digital license, you need to install Windows 10 Home.
The message includes links to learn more about Windows Activation, open the Microsoft Store to purchase a genuine copy of Windows, or launch the "hardware change" process.
Attempts to activate the operating system again fail at the time. Reinstallation or the installation of backups don't fix the issue either.
Administrators who check the Event log will find Even ID 8198 listings:
License Activation (slui.exe) failed with the following error code: hr=0xC004C003
Microsoft Support published a statement on Microsoft Answers that confirms the issue.
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
Microsoft is aware of the issue and working on a fix to correct it. The company advises users to ignore activation messages for the time being. It is not necessary to do anything on the user side as the issue is server side only.
Microsoft stated that it will update the official thread on the Microsoft Answers forum when the issue is resolved. Windows 10 PCs should change the status to activated again once the issue is resolved and the notification that the license is for Windows 10 Home while Windows 10 Pro is installed should go away as well once the issue is resolved. (via Windows Latest and Born)