1.Windows 10 isn't activated after upgrading for free from Windows 7 SP1 or Windows 8.1 Update
2.This product key didn't work. (Error code: 0xC004C003), License could not be found or was invalid. (Error code: 0xC004F034)
3.Genuine Validation detected tampered Windows binaries. (Error code: 0xC004C4AE).
4.The Software Licensing Service determined that this specified product key can only be used for upgrading, not for clean installations. (Error code: 0xC004F061)
5.A networking problem has occurred while activating your copy of Windows. (Error code: 0xC004FC03)
6.The activation server reported that the product key has exceeded its unlock limit. (Error code: 0xC004C008)
7.The activation server reported that the Multiple Activation Key has exceeded its limit. (Error code: 0xC004C020)
8.DNS name does not exist. (Error code: 0x8007232B)
The filename, directory name, or volume label syntax is incorrect. (Error code: 0x8007007B)
9.A security error occurred. (Error code: 0x80072F8F)
10.The Software Licensing Service reported that the license evaluation failed. (Error code: 0xC004E003)
11.The Software Licensing Service reported that the license evaluation failed. (Error code: 0xC004E003)
12.Unspecified error. (Error code: 0x80004005)