I'm trying to start an app in Visual Studio 2017 and Xamarin, when I login to App.xaml.cs, I get this error the name of the type or name space xamarin was not found in several points, maybe I have to install something else.
I had the same error and only with updating xamarin.forms in the NuGet package corrected In references, right click and select, manage NuGet packages, search for xamarin.forms, click and update.