Hello. Today i decided to upgrade my Windows 8.1 pro (x64, en-us) pc to Windows 10 pro using windows update method. After some time it finally upgraded and it said that windows was activated. After that I decided to do a clean install of the os using the iso from MSDN: File:en_windows_10_multiple_editions_x64_dvd_6846432.ISO Size:3.9GB CRC32:B1A4699E MD5:23E397A21A9E01F141C64B7E1260314A SHA-1:60CCE9E9C6557335B4F7B18D02CFE2B438A8B3E2 However, after doing that it said that windows cannot be activated and that the key has been blocked. But here is the strange part. After that I decided to make an iso image using media creation tool that microsoft provided, and after i did that and did a clean install with the iso I made it said that my windows is activated. What is the deal?? Both windows versions were the same (en-us, x64, windows 10 pro).
It's either that or that the two images had different installation information that windows activation server look for, unless ofcourse other people were successful in activating their system using image MSDN provided, then i take my words back.
Leaving the key fields empty when installing Windows, and/or removing the key from Win10 completely and letting Windows choose the key for you will most likely fix the issue.
I had the same issue, upgrade from 8.1 , activated, then tried clean install over 4-5 times on a new HDD , the darn thing could not be activated! finally I decided to create a recovery USB from the activated install, then used that USB i installed new win10 on the other HDD , activated immediately! don't know if the recovery USB has some 'activation' info into it...