title: Value cannot be null. Parameter name: userContext in Visual Studio 2017
body: <p>I am facing a strange issue that, getting a message as "Value can not be null. Parameter name is userContext" while clicking on Extensions and updates under tools menu. </p>
  
  <p><a href="https://i.stack.imgur.com/kNDJZ.png" rel="noreferrer"><img src="https://i.stack.imgur.com/kNDJZ.png" alt="enter image description here"></a></p>
  
  <p>Please do let me know what is the workaround for this issue. Thank you.</p>