title: Razor Pages Validation Summary ModelOnly Does Not Show Model Errors
body: <p>I am trying to use the ModelOnly setting on the validation summary. So it does not repeat the errors for the properties so I can show a Model error from the server (If I set it to <code>All</code> it works but shows the repeated property errors)</p>
  <pre><code>&lt;div asp-validation-summary=&quot;ModelOnly&quot;&gt;&lt;/div&gt;
  </code></pre>
  <p>However, I cannot get it to show any errors. I am adding a Model error to the ModelState (As shown below) but they do not show up in the summary? I have tried with AND without a key shown below!</p>
  <pre><code>ModelState.AddModelError(&quot;WithAKey&quot;, &quot;My Model Error&quot;);
  ModelState.AddModelError(&quot;&quot;, &quot;My Model Error&quot;);
  </code></pre>
  <p>Neither of these work? What have I missed?</p>