Error 0xC004F069 on Activating Windows 8.1

An error occurred when trying to activate my Windows 8.1. I searched for a solution online and found out that the error code given in the error message means there is a mismatch in the SKU. How can I activate Windows 8.1? Please help.

Windows Activation
An error has occurred
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Code:
0xC004F069
Description:
The Software Licencing Service reported that the product SKU is not found.
