Today I tried to upgrade my Windows 8 laptop to Windows 8.1. Normally the upgrade is performed by opening the Windows store and clicking on the Windows 8.1 upgrade link. 

However, on this computer the upgrade link did not appear. Searching the Internet revealed no magic link to the Windows 8.1 upgrade redistributable.

Since the upgrade had been released on October 17th, I knew that it must still be available to Windows 8 users.

Then it dawned on me, that one of my other computers would not find the Windows 8.1 upgrade until I had gone to Windows Update and loaded all the pending updates.

Once the Windows 8 updates were current, then the Windows 8.1 update is visible at the Windows Store and it installs directly from there.