title: Xamarin.Forms with Prism not building in Visual Studio 2017 15.7.2
body: <p>I have a Xamarin.Forms with Prism MVVM, having build problem in Visual Studio 2017 15.7.2.</p>
  
  <p>This project was created in Visual Studio 2017 15.6.2, with Prism template, and was working perfectly.</p>
  
  <p>I decided to update my IDE from 15.6.2 to 15.7.2, and my project stops working, getting the error below:</p>
  
  <pre><code>Severity    Code    Description Project File    Line    Suppression State
  Error       Your project is not referencing the "MonoAndroid,Version=v8.1" framework. Add a reference to "MonoAndroid,Version=v8.1" in the "frameworks" section of your project.json, and then re-run NuGet restore.    AppPrivateCard.Android          
  
  A Xamarin.Forms project do not have project.json file, as suggested by the error message, and I already modified the target Android version to Android 27 version (Android Oreo 8.1), but the error persists.
  </code></pre>
  
  <p>I have already update Xamarin.Forms to 3.0.0.482510 and nothing.</p>
  
  <p>But, if I create a Xamarin project without Prism, using VS 2017 15.7.2, and update all references, it builds without this error. So, I think the problem is the Prism template.</p>
  
  <p>One option for me is to downgrade the VS 2017, but I would rather not.</p>