Note: I tagged this article with “MVVM” because I got a few support requests for MVVM Light regarding this exact issue. In fact it is a Windows 8 issue and has nothing to do with MVVM Light per se… Sometimes when you work on a Windows 8 app, you will get a very annoying issue when starting the app. In that case, the app doesn’t not even start past the Splash screen. Putting a breakpoint in App.xaml.cs doesn’t help because the app doesn’t even reach that point! So what exactly is happening? Well when a Windows 8 app
starts, the system is performing a few check first. One of the checks, for instance, is to see if an app with the same package ID is already available. The package ID is a unique value set in the package manifest. In the Solution Explorer, double click on Package.appxmanifest. This opens the manifest in a special editor Click on the Packaging tab See the GUID under Package Name. This is the unique ID I am talking about.