title: ASP CORE debugging in VS: "adding namespace will prevent the debug session from continuing" error
body: <p>When the debugging process opens Razor file it is become impossible to make next step (F10, F11) because of VS is blocked by the error "File was modified: Continue or Stop". Also this message appears in the VS Errors list:</p>
  
  <p><a href="https://i.stack.imgur.com/HKe6I.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/HKe6I.png" alt="enter image description here"></a></p>
  
  <p>Closing of the tab with the "modified" razor file somehow helps - error is gone - and then it is possible to continue debugging.</p>
  
  <p>It seems like VS changes the file by its own, but there is no any sign of this except this message.</p>
  
  <p>Why and where  VS adds this 'namespace' ? Knowing this I would add this 'namespace' by myself to my code and then VS will not have a reason to change the code and interrupt debugging. </p>