title: Failure to Install Microsoft.AspNetCore.AppRef
body: <p>When I tried installing <code>Microsoft.AspNetCore.AppRef</code> in my webapplication in .net core 3.1.</p>
  <p>However, I get this error instead:</p>
  <pre class="lang-none prettyprint-override"><code>Package 'Microsoft.AspNetCore.App.Ref 3.1.3' has a package type 'DotnetPlatform' that is not supported by project 'xxxxxx'.             
  NU1213 The package Microsoft.AspNetCore.App.Ref 3.1.3 has a package type DotnetPlatform that is incompatible with this project.         
  </code></pre>
  <p>Any ideas how to fix?</p>