title: Cannot debug T4 template in VS2017
body: <p>In VS2017 Community, I cannot debug T4 Templates, which works in 2015.</p>
  
  <p>I have a very basic template, such as this...</p>
  
  <pre><code>&lt;#@ template debug="true" hostspecific="false" language="C#" #&gt;
  &lt;#@ output extension=".txt" #&gt;
  &lt;#
  var a = "Hello";
  var b = "World";
  #&gt;
  &lt;#=($"{a} {b}!")#&gt;
  </code></pre>
  
  <p><code>Run Custom Tool</code> and <code>Transform All T4 Templates</code> both options work, and text file contains expected output</p>
  
  <blockquote>
    <p>Hello World!</p>
  </blockquote>
  
  <p>If I put breakpoint somewhere and use <code>Debug T4 Template</code> from the context menu of .tt, it throws this error</p>
  
  <blockquote>
    <p>Unable to start transformation run creation process.</p>
  </blockquote>
  
  <p>However it works fine in VS 2015, and I'm able to debug there.</p>
  
  <p>What I could be missing? how to debug T4 Templates in VS 2017? Note that I don't have any Tool/ Extension installed in VS2015 to debug T4</p>