title: Magento Website Redirect to Downloader page
body: <p>I tried to log in to the admin page of my magento website.
  But is shows the redirect loop error.
  When I go the the index page it redirect to the downloader page.
  <a href="https://i.stack.imgur.com/Lo53O.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Lo53O.png" alt="enter image description here"></a>
  Manually clear the var/cache var/session folders, but do not work.
  Also tried change web/url/base_url from 1 to 0, not work.
  It maybe missing the mage.php file, but no idea what's that file, and how to fix the issue.
  Can anyone help me to figure it out?
  Thanks a lot!</p>