I’ve had this problem on a machine that I’m trying to upgrade to Windows 8.1 from 8. I’d been searching for solutions for a couple days and ran across this post.
The simple solution is to run the following command in the Command Prompt (with administrator privileges):
powershell -ExecutionPolicy Unrestricted Add-AppxPackage -DisableDevelopmentMode -Register $Env:SystemRoot\WinStore\AppxManifest.xml
This will fix the issue. The Windows Store will reload everything and you’ll be able to get in. I hope this helps someone!