Windows 8.1 apps won’t open or load

This has happened to me on my windows 8 machine, I did a little searching and found that the entire windows 8 needed an update, to update windows 8 open the charm bar (on touch slide finger in from right, with mouse put it in top right corner) once the charm bar is open look at the bottom and select "Settings", in settings go to the bottom and hit the "Change PC settings" button, once this menu opens on the right panel select "Windows Update", if there is a update click the update button, but if it displays no update hit the "Check for updates now" button. If all else fails you can refresh your pc, refreshing your pc will keep all your personal items like files music and such, to refresh your pc, navigate to the PC settings (You should already be here) and in the right panel select "general" scroll down in the General settings until you find the "Refresh your PC without affecting your files" then hit the "get started" button. Hope this helped!

Those symptoms were caused by the fact that the registered packages had a higher version than the packages actually available in "C:\Program Files\WindowsApps". (Such a bug in 2018, no comment ...)

To fix it, I had to manually uninstall the packages in Powershell, then install the versions available. You can follow this simple procedure if you are in the same situation :

1. Accessing WindowsApps : follow this guide to take ownership of "C:\Program Files\WindowsApps";

Note : I will take the calculator as example, you have to repeat the following procedure for every broken app. There might be an automated way to do it with a powershell script, but I don't know about it.

2. Find out the registered version of your broken app :
   • Open the console in admin mode and type "powershell" ;
   • Type Get-AppXPackage -Name "*calc*" (replace calc by what's relevant for you. The * is a regular expression meaning it can be replaced by anything) ;
   • In the results displayed, find out the PackageFullName line, and copy/paste this name in notepad so you don't lose it. If you don't find any folder with the same name in the WindowsApps folder, it means you have identified at least part of your problem ! In my case :

3. Find out the last available package : go in your WindowsApps folder, and find the folder with the last version of calculator (the one with "x64" in its name), in my case :

4. Unregister the broken version : back to the powershell, enter the command :

(Obviously replace the package name depending on your situation)

Remove-AppxPackage -Package "Microsoft.WindowsCalculator_10.1712.3351.0_x64__8wekyb3d8bbwe"

5. Register the available package :

(The folder you found at step 3)

Add-AppxPackage -DisableDevelopmentMode -Register "C:\Program Files\WindowsApps\Microsoft.WindowsCalculator_10.1706.2406.0_x64__8wekyb3d8bbwe\AppxManifest.xml"

6. Update the app : Simply launch Microsoft Store, click the "..." on the top right corner, then "Download and Update". Then click "Get update", and the store will update your app to their last version. Note that if the store itself is broken you can fix it the same way than I showed you with Calculator.

And if you didn't get any error message at this point, your problem should be fixed !