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).