Windows 8 - Enable the Built-in Administrator account.

To resolve the issue with updating to Windows 8.1, follow these steps:

Step 1:

Enable the Built-in Administrator account.

a) Press Windows and x key together on your desktop screen.
b) Click on Command Prompt (admin).
c) Type: net user administrator /active: yes

Note: Please follow the same steps and type net user administrator /active: no to disable admin account after the troubleshooting is done.

Step 2:

After enabling Built-in admin account, refer to the article to update to Windows 8.1 operating system:

Update to Windows 8.1 from Windows 8

http://windows.microsoft.com/en-in/windows-8/update-from-windows-8-tutorial