title: Cannot start lambda with Mock Lambda Test Tool
body: <p>I've been working with AWS lambdas for a few months. I was working with a lambda and it was fine at the end of the day. I came back to work on it the next day, and I can't get Visual Studio to even start the application using the Mock Lambda Test Tool.</p>
  
  <p>I ended up creating an empty lambda that just returns the input (the standard project code that AWS gives you as a template) and that won't even run. I hit the play button to star the Mock Lambda Test Tool, it looks like it will run for a couple seconds, then it closes down. The command window does not even pop up. </p>
  
  <p>This is the code from the template project.</p>
  
  <pre><code>public string FunctionHandler(string input, ILambdaContext context)
  {
      return input?.ToUpper();
  }
  </code></pre>
  
  <p>This is all I get in the output window of VS:</p>
  
  <blockquote>
    <p>The target process exited without raising a CoreCLR started event.
    Ensure that the target process is configured to use .NET Core. This
    may be expected if the target process did not run on .NET Core. The
    program '[16700] dotnet-lambda-test-tool-2.1.exe: Program Trace' has
    exited with code 0 (0x0). The program '[16700]
    dotnet-lambda-test-tool-2.1.exe' has exited with code -2147450726
    (0x8000809a).</p>
  </blockquote>
  
  <p>I have tried re-installing the AWS toolkit, and also tried re-installing Visual Studio. This is an issue with VS 2017 and VS 2019. I just installed 2019 to see if that would fix the issue. Any help would be appreciated.</p>