title: Xamarin Form Error Value cannot be null. Parameter name: type
body: <p>All day I was receiving this very clear (not the sarcasm) error message &quot;<em>Value cannot be null.  Parameter name: type</em>&quot;  I was hitting my head against the wall slowly decomposing my code until I could figure out the exact cause of the problem.  After much tedious deconstruction I discovered that I had an error in my <code>GestureRecognizers</code> section.  The problem was that I accidentally typed Command to try to pass a parameter instead of <code>CommandParameter</code>.</p>
  <p>My original code generating the error looked like this.</p>
  <pre class="lang-xml prettyprint-override"><code>&lt;Label.GestureRecognizers&gt;
      &lt;TapGestureRecognizer Tapped=&quot;Value_Tapped&quot; Command=&quot;language&quot; /&gt;
  &lt;/Label.GestureRecognizers&gt;
  </code></pre>
  <p>The corrected code is this:</p>
  <pre class="lang-xml prettyprint-override"><code>&lt;Label.GestureRecognizers&gt;
      &lt;TapGestureRecognizer Tapped=&quot;Value_Tapped&quot; CommandParameter=&quot;language&quot; /&gt;
  &lt;/Label.GestureRecognizers&gt;
  </code></pre>
  <p>I hope this helps someone else in the future.</p>