title: UWP UnitTest debugging "Unable to attach to CoreCLR"
body: <p>I'm having issues running Debug mode for unit tests in my UWP (Windows 10) project. The error thrown is:</p>
  
  <p><code>Unable to attach to CoreCLR. Interop debugging is not supported.</code></p>
  
  <p>The output from the test window shows:</p>
  
  <pre><code>Deployment complete (0:00:00,932). Full package name: "d13697af-b51e-4d46-bbce-4f4b89a44a95_1.0.0.0_x64__h20887da7bcmm"
  
  A user callback threw an exception.  Check the exception stack and inner exception to determine the callback that failed.
  </code></pre>
  
  <p>The really weird thing is that this does not happen every time. I have successfully debugged my unit tests a couple of times now, until it fails. The remedy seems to be to clean the solution and rebuild, after which it sometimes (not always) works again for a few attempts. Then it starts failing and I need to clean again.</p>
  
  <p>I'm building for Windows 10 build 10586, selecting another version doens't seem to make a different though. </p>