title: How do I fix "The active test run was aborted" in Visual Studio's Test Explorer?
body: <p>"Run All" from "Test Explorer" does not complete (VS2017 Enterprise) anymore.  It stalls with Passed (411), Not Run (309).  The counts vary a little, usually roughly half and half.</p>
  
  <p>The output window (Visual Studio | Output tab | Show output from:  Tests) contains the following error message:</p>
  
  <p>"The active test run was aborted. Reason: Unhandled Exception: System.AppDomainUnloadedException: Attempted to access an unloaded AppDomain."</p>
  
  <p>The tests continue to run fine in ReSharper (720 of 720 pass).  R# is where I usually run my tests.  I jump over to Microsoft's "Test Explorer" when I am trying to Analyze Code Coverage (though the tests stall with or without code coverage).  It (Analyze Code Coverage) worked as recently as 5/15/2018 (and at least a half dozen to a dozen times before that).
  <a href="https://i.stack.imgur.com/Qed3x.png" rel="noreferrer"><img src="https://i.stack.imgur.com/Qed3x.png" alt="enter image description here"></a></p>