Source: msdn.com
The original articles states that:
I had the 2nd and 3rd issue. App Store showed 15 updates on each restart and when I tried to open it I was welcomed with a message saying that it was impossible to connect to the store right now and "retry". By hitting retry, the store opened but no updates were waiting for me. And I was running Windows 8 so it applies to 8 instead of 8.1. Running the first fix (right below) fixed this issue.
powershell -ExecutionPolicy Unrestricted Add-AppxPackage -DisableDevelopmentMode -Register $Env:SystemRoot\WinStore\AppxManifest.XML
powershell -ExecutionPolicy Unrestricted Add-AppxPackage -DisableDevelopmentMode -Register $Env:SystemRoot\camera\AppxManifest.xml
powershell -ExecutionPolicy Unrestricted Add-AppxPackage -DisableDevelopmentMode -Register $Env:SystemRoot\FileManager\AppxManifest.xml
powershell -ExecutionPolicy Unrestricted Add-AppxPackage -DisableDevelopmentMode -Register $Env:SystemRoot\ImmersiveControlPanel\AppxManifest.xml