MSDN: In some cases, a type that you used in a .NET Framework desktop app doesn't exist within the .NET APIs for Metro style apps. Instead, you can use a type from the Windows Runtime. For example, the System. IO. IsolatedStorage. IsolatedStorageSettings class isn't included in the .NET APIs for Metro style apps, but the Windows.Storage.ApplicationDataContainer class provides similar behavior for storing app settings. Examples of common changes you might have to make are included in the section Converting your existing .NET Framework code.