title: How to Resolve Exception: Cannot create an instance of "WindowsPage"
body: <p>Brand new to Xamarin forms here and trying to get started in cross platform app development using the package. However right out of the gate I seem to be running into an issue that has been asked a few times elsewhere but I haven't really seen an actual response on. Currently I'm trying to work on the UWP / Universal Windows / Windows 10 User Interface in a Portable Forms / PCL setup.</p>
  
  <p>It's the Cannot create an instance of WindowsPage error message in the Microsoft Visual Studio 2015 Xaml designer. I'm following the guide at <a href="https://developer.xamarin.com/guides/xamarin-forms/platform-features/windows/installation/universal/" rel="nofollow">https://developer.xamarin.com/guides/xamarin-forms/platform-features/windows/installation/universal/</a> so I added the line for "xmlns:forms="using:Xamarin.Forms.Platform.UWP" the xaml file before changing the page tag from Page to forms:WindowsPage thus referencing the xamarin forms package. I did update all the NuGet packages to the latest version. Xamarin forms is something like 2.2 at the moment.</p>
  
  <p>I initially installed the defaults for the VS2015 Xamarin package and I just tried modifying that installation with every extra component included so I don't think I'm missing anything there. I believe Xamarin is installed properly since it shows up in the Help -> Xamarin menu and I can choose new solutions out of the Xamarin forms package but I'm not sure what could be causing the issue.</p>
  
  <p>Here's the XAML code</p>
  
  <pre><code>&lt;forms:WindowsPage
      x:Class="SoloPathfinderPCL.UWP.MainPage"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:forms="using:Xamarin.Forms.Platform.UWP"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:local="using:SoloPathfinderPCL.UWP"
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
      mc:Ignorable="d"&gt;
  
  &lt;/forms:WindowsPage&gt;
  </code></pre>
  
  <p>Here's my Stack Trace for Exception: Cannot create an instance of "WindowsPage".</p>
  
  <pre><code>at Microsoft.VisualStudio.DesignTools.Platform.InstanceBuilders.InstanceBuilderOperations.InstantiateType(Type type, Boolean supportInternal)
     at Microsoft.VisualStudio.DesignTools.Platform.InstanceBuilders.ClrObjectInstanceBuilder.InstantiateTargetType(IInstanceBuilderContext context, ViewNode viewNode)
     at Microsoft.VisualStudio.DesignTools.Platform.InstanceBuilders.ClrObjectInstanceBuilder.Instantiate(IInstanceBuilderContext context, ViewNode viewNode)
     at Microsoft.VisualStudio.DesignTools.WindowsXamlDesigner.InstanceBuilders.FrameworkElementInstanceBuilder.Instantiate(IInstanceBuilderContext context, ViewNode viewNode)
     at Microsoft.VisualStudio.DesignTools.WindowsXamlDesigner.InstanceBuilders.UserControlInstanceBuilder.Instantiate(IInstanceBuilderContext context, ViewNode viewNode)
     at Microsoft.VisualStudio.DesignTools.Platform.InstanceBuilders.ViewNodeManager.CreateInstance(IInstanceBuilder builder, ViewNode viewNode)
  </code></pre>
  
  <p>Hope someone can point me and everyone else having this issue in the right direction. Thanks.</p>