title: Unfortunately, MyApp.Android has stopped. with ContentPage.Resource in XAML file
body: <p>I am starting to build up a UI on Android using Xamarin Forms.My <code>XAML</code> file is give below.</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8" ?&gt;
  &lt;ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
               xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
               xmlns:PortableViews="clr-namespace:MyApp.Portable.Views"
               x:Class="MyApp.Portable.Views.MainPage3"&gt;
  
    &lt;ContentPage.Resources&gt;
      &lt;PortableViews:NullVisibilityConverter x:Key="NullVisibilityConverter"/&gt;
    &lt;/ContentPage.Resources&gt;
  &lt;Grid&gt;  
  &lt;/Grid&gt;
  &lt;/ContentPage&gt;
  </code></pre>
  
  <p>I am able to compile and deploy into the device.When I run the app from the device I get the error saying 
  <code>Unfortunately, MyApp.Android has stopped.</code></p>
  
  <p>If I comment out <code>&lt;ContentPage.Resources&gt;</code> tag It runs and shows me a blank screen. Why is wrong with </p>
  
  <pre><code>&lt;ContentPage.Resources&gt;
          &lt;PortableViews:NullVisibilityConverter x:Key="NullVisibilityConverter"/&gt;
  &lt;/ContentPage.Resources&gt;
  </code></pre>
  
  <p>logcat shows the following message.</p>
  
  <p><code>11-10 14:01:39.675 I/DEBUG ( 2131): [OnPurpose Redunant in void preset_info(aed_report_record*, int, int)] pid: 2058, tid: -1361051648, name: UNKNOWN &gt;&gt;&gt; MyApp.Android.MyApp.Android</code></p>
  
  <p>If I look at <code>Android Runtime</code> in logcat I get the following errors.</p>
  
  <pre><code>11-10 14:42:18.554 E/AndroidRuntime( 4487): FATAL EXCEPTION: main
  11-10 14:42:18.554 E/AndroidRuntime( 4487): Process: MyApp.Android.MyApp.Android, PID: 4487
  11-10 14:42:18.554 E/AndroidRuntime( 4487): java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
  11-10 14:42:18.554 E/AndroidRuntime( 4487):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:750)
  11-10 14:42:18.554 E/AndroidRuntime( 4487): Caused by: java.lang.reflect.InvocationTargetException
  11-10 14:42:18.554 E/AndroidRuntime( 4487):     at java.lang.reflect.Method.invoke(Native Method)
  11-10 14:42:18.554 E/AndroidRuntime( 4487):     at java.lang.reflect.Method.invoke(Method.java:372)
  11-10 14:42:18.554 E/AndroidRuntime( 4487):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:955)
  11-10 14:42:18.554 E/AndroidRuntime( 4487):     ... 1 more
  11-10 14:42:18.554 E/AndroidRuntime( 4487): Caused by: android.runtime.JavaProxyThrowable: Xamarin.Forms.Xaml.XamlParseException: Position 13:6. Type Window not found in xmlns http://xamarin.com/schemas/2014/forms
  11-10 14:42:18.554 E/AndroidRuntime( 4487):   at Xamarin.Forms.Xaml.ApplyPropertiesVisitor.GetRealNameAndType (System.Type&amp; elementType, System.String namespaceURI, System.String&amp; localname, Xamarin.Forms.Xaml.HydratationContext context, IXmlLineInfo lineInfo) &lt;0x7f59f99ac0 + 0x0013c&gt; in &lt;filename unknown&gt;:0 
  11-10 14:42:18.554 E/AndroidRuntime( 4487):   at Xamarin.Forms.Xaml.ApplyPropertiesVisitor.SetPropertyValue (System.Object xamlelement, XmlName propertyName, System.Object value, Xamarin.Forms.BindableObject rootElement, INode node, Xamarin.Forms.Xaml.HydratationContext context, IXmlLineInfo lineInfo) &lt;0x7f59fb3160 + 0x0013b&gt; in &lt;filename unknown&gt;:0 
  11-10 14:42:18.554 E/AndroidRuntime( 4487):   at Xamarin.Forms.Xaml.ApplyPropertiesVisitor.Visit (Xamarin.Forms.Xaml.ElementNode node, INode parentNode) &lt;0x7f59f9e048 + 0x005eb&gt; in &lt;filename unknown&gt;:0 
  11-10 14:42:18.554 E/AndroidRuntime( 4487):   at Xamarin.Forms.Xaml.ElementNode.Accept (IXamlNodeVisitor visitor, INode parentNode) &lt;0x7f59fc4658 + 0x00277&gt; in &lt;filename unknown&gt;:0 
  11-10 14:42:18.554 E/AndroidRuntime( 4487):   at Xamarin.Forms.Xaml.RootNode.Accept (IXamlNodeVisitor visitor, INode parentNode) &lt;0x7f59fc3ed8 + 0x000ff&gt; in &lt;filename unknown&gt;:0 
  11-10 14:42:18.554 E/AndroidRuntime( 4487):   at Xamarin.Forms.Xaml.XamlLoader.Load (Xamarin.Forms.BindableObject view, System.String xaml) &lt;0x7f5a924650 + 0x00387&gt; in &lt;filename unknown&gt;:0 
  11-10 14:42:18.554 E/AndroidRuntime( 4487):   at Xamarin.Forms.Xaml.XamlLoader.Load (Xamarin.Forms.BindableObject view, System.Type callingType) &lt;0x7f5a99ba20 + 0x00053&gt; in &lt;filename unknown&gt;:0 
  11-10 14:42:18.554 E/AndroidRuntime( 4487):   at Xamarin.Forms.Xaml.Extensions.LoadFromXaml[TView] (Xamarin.Forms.Xaml.TView view, System.Type callingType) &lt;0x7f5a99b9d8 + 0x00023&gt; in &lt;filename unknown&gt;:0 
  11-10 14:42:18.554 E/AndroidRuntime( 4487):   at MyApp.Portable.Views.MainPage3.InitializeComponent () &lt;0x7f5a99b950 + 0x0002b&gt; in &lt;filename unknown&gt;:0 
  11-10 14:42:18.554 E/AndroidRuntime( 4487):   at MyApp.Portable.Views.MainPage3..ctor () &lt;0x7f5a9bf0d0 + 0x0001f&gt; in &lt;filename unknown&gt;:0 
  11-10 14:42:18.554 E/AndroidRuntime( 4487):   at MyApp.Portable.App..ctor () &lt;0x7f5b4276f8 + 0x0002f&gt; in &lt;filename unknown&gt;:0 
  11-10 14:42:18.554 E/AndroidRuntime( 4487):   at MyApp.Android.MainActivity.OnCreate (Android.OS.Bundle bundle) &lt;0x7f5b457370 + 0x00043&gt; in &lt;filename unknown&gt;:0 
  11-10 14:42:18.554 E/AndroidRuntime( 4487):   at Android.App.Activity.n_OnCreate_Landroid_os_Bundle_ (IntPtr jnienv, IntPtr native__this, IntPtr native_savedInstanceState) &lt;0x7f5b457080 + 0x00063&gt; in &lt;filename unknown&gt;:0 
  11-10 14:42:18.554 E/AndroidRuntime( 4487):   at (wrapper dynamic-method) System.Object:5c4437ec-ddbf-41de-b890-3c31365af092 (intptr,intptr,intptr)
  11-10 14:42:18.554 E/AndroidRuntime( 4487):     at md5b10bea1896ca4a98de5581931a9e1765.MainActivity.n_onCreate(Native Method)
  11-10 14:42:18.554 E/AndroidRuntime( 4487):     at md5b10bea1896ca4a98de5581931a9e1765.MainActivity.onCreate(MainActivity.java:29)
  11-10 14:42:18.554 E/AndroidRuntime( 4487):     at android.app.Activity.performCreate(Activity.java:5971)
  11-10 14:42:18.554 E/AndroidRuntime( 4487):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1111)
  11-10 14:42:18.554 E/AndroidRuntime( 4487):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2413)
  11-10 14:42:18.554 E/AndroidRuntime( 4487):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2522)
  11-10 14:42:18.554 E/AndroidRuntime( 4487):     at android.app.ActivityThread.access$800(ActivityThread.java:167)
  11-10 14:42:18.554 E/AndroidRuntime( 4487):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1417)
  11-10 14:42:18.554 E/AndroidRuntime( 4487):     at android.os.Handler.dispatchMessage(Handler.java:111)
  11-10 14:42:18.554 E/AndroidRuntime( 4487):     at android.os.Looper.loop(Looper.java:194)
  11-10 14:42:18.554 E/AndroidRuntime( 4487):     at android.app.ActivityThread.main(ActivityThread.java:5534)
  11-10 14:42:18.554 E/AndroidRuntime( 4487):     ... 4 more
  </code></pre>