title: Problem in changing target framework in visual studio 2017 (xamarin)
body: <p>i am new to Xamarin.
  i have a problem changing target framework. below i described the problem.
  Before.</p>
  
  <pre><code>[enter image description here][1]
  [enter image description here][2]
  [enter image description here][3]
  [enter image description here][4]
  **After:**
  [enter image description here][5]
  [enter image description here][6]
  [enter image description here][7]
  [enter image description here][8]
  
  *Please help.*
  
  
    [1]: https://i.stack.imgur.com/KgmPa.png
    [2]: https://i.stack.imgur.com/tx6mG.png
    [3]: https://i.stack.imgur.com/I1w0Q.png
    [4]: https://i.stack.imgur.com/Oe3Oj.png
    [5]: https://i.stack.imgur.com/16Jn7.png
    [6]: https://i.stack.imgur.com/tyrFH.png
    [7]: https://i.stack.imgur.com/5Urc8.png
    [8]: https://i.stack.imgur.com/aQumk.png
  </code></pre>