master:8088 web ui in history shows unable to connect in hadoop 2.7.2 : after running the job , in master:8088 ,when I click History it shows unable to connect.
[![history][1]][1]

[![unable to connect][2]][2]


  [1]: https://i.stack.imgur.com/f2Pve.png
  [2]: https://i.stack.imgur.com/J5skl.png