Get Win8.1 update failed mainly may be several reasons:

1, installed before the early WCP, WPR version of Win8.
2, Windows Professional Edition (VOL large customers Edition), activated using KMS method Windows 8 Professional Edition
3, Windows 8 Enterprise Edition
4, using MSDN ISO image is installed, but the use of multiple activation key to activate the Windows 8 version.
5, there is no update patch installed KB 2871839