Windows 10 Photos shows "Invalid Value for Registry"

When trying to open a picture, for example a JPEG, with Windows 10 picture the error message "Invalid Value for Registry" or "Ungültiger Wert für Registrierung" is shown. 

How to fix it:
English Windows 10: Start ➞ type "Photos" ➞ Rightclick ➞ App Settings ➞ Repair
German WIndows 10: Start ➞ "Fotos" eingeben ➞ Rechtsklick ➞ App Einstellungen ➞ Reparieren

If pressing the "Repair" button does not help, try the "Reset" button. "Repair" helped me with my problem. If not I'd probably use Microsoft sysinternals procmon to troubleshoot the issue.