title: It is "not supported" to build or publish a self-contained application without specifying a RuntimeIdentifier
body: <p>Using the latest Visual Studio 2019 I am trying to publish a Msix installer for a DotNetCore 3.1 WPF application. The application builds and runs correctly, but when I try to publish the application I get this error</p>
  <p><code>It is not supported to build or publish a self-contained application without specifying a RuntimeIdentifier.</code></p>
  <p>My UI projects csproj looks like this.</p>
  <pre><code>&lt;PropertyGroup&gt;
      &lt;OutputType&gt;WinExe&lt;/OutputType&gt;
      &lt;TargetFramework&gt;netcoreapp3.1&lt;/TargetFramework&gt;
      &lt;UseWPF&gt;true&lt;/UseWPF&gt;
      &lt;RuntimeIdentifier&gt;win10-x64&lt;/RuntimeIdentifier&gt;
      &lt;SelfContained&gt;false&lt;/SelfContained&gt;
  &lt;/PropertyGroup&gt;
  </code></pre>
  <p>How can this issue be fixed?</p>
  <p>Edit: So it turns out that the issue only occurs when I include my self hosted asp.net core project in the gui project that I am trying to package.</p>
  <p>What could be causing this issue? Is it just not supported to package that kind of project for some reason?</p>