title: Error message 'Value cannot be null. Parameter name: userContext' in Visual Studio 2017
body: <p>I get error message</p>
  
  <blockquote>
    <p>'Value cannot be null. Parameter name: userContext'</p>
  </blockquote>
  
  <p>in Visual Studio 2017 when trying to click notification or opening Extensions and updates from tools folder. 
  Before answering can you look <a href="https://stackoverflow.com/a/44977569/8225828">this Answer</a>. The answer did not work on me.</p>