title: Uno App exception launch missing windows.color
body: <p>I just migrated my app to use Uno 4.0 and am having a few issues.  When I go to build and run the project- I am getting this error:</p>
  <blockquote>
  <p>System.MissingFieldException
  Message=Field not found: Windows.UI.Color Windows.UI.Colors.Black Due to: Could not find field in class</p>
  </blockquote>
  <p>I do use the colors in my MaterialColorPaletteOverride.xaml.  I currently have Uno.Material at 1.0.507.  I plan to migrate that- but would like to resolve this issue first.  This code did work before the migration- so I think somehow the colors are referenced differently now.</p>
  <p>I am using the following packages:</p>
  <ul>
  <li>Uno.Core 4.0.1</li>
  <li>Uno.Material 1.0.0.-dev.507</li>
  <li>Uno.UI 4.0.7</li>
  <li>Microsoft.UI.Xaml 2.7.0</li>
  </ul>
  <p>Here is my snippet from my MaterialColorPaletteOverride.xaml:</p>
  <pre class="lang-xml prettyprint-override"><code>    &lt;ResourceDictionary
         xmlns=&quot;http://schemas.microsoft.com/winfx/2006/xaml/presentation&quot; 
         xmlns:x=&quot;http://schemas.microsoft.com/winfx/2006/xaml&quot;
         xmlns:local=&quot;using:NeatApp.Shared&quot;&gt;
             &lt;ResourceDictionary.ThemeDictionaries&gt;
             &lt;!-- Light Theme --&gt;
             &lt;ResourceDictionary x:Key=&quot;Light&quot;&gt;
                 &lt;SolidColorBrush x:Key=&quot;MaterialOnBackgroundBrush&quot; Color=&quot;Black&quot;/&gt;
             &lt;/ResourceDictionary&gt;
             &lt;!-- Dark Theme --&gt;
             &lt;ResourceDictionary x:Key=&quot;Dark&quot;&gt;
                 &lt;SolidColorBrush x:Key=&quot;MaterialOnBackgroundBrush&quot; Color=&quot;White&quot;/&gt;
             &lt;/ResourceDictionary&gt;
         &lt;/ResourceDictionary.ThemeDictionaries&gt;    
      &lt;/ResourceDictionary&gt;
  </code></pre>