title: codeigniter 3.1 upgradation showing error The configuration file url.php does not exist
body: <p>codeigniter 3.1 upgradation showing error The configuration file url.php does not exist.While the log file doesn't showing exact error. Here is the log details</p>
  
  <p><img src="https://i.stack.imgur.com/bdHSy.png" /></p>
  
  <pre><code>INFO - 2017-05-14 22:11:57 --&gt; Config Class Initialized
  INFO - 2017-05-14 22:11:57 --&gt; Hooks Class Initialized
  DEBUG - 2017-05-14 22:11:57 --&gt; UTF-8 Support Enabled
  INFO - 2017-05-14 22:11:57 --&gt; Utf8 Class Initialized
  INFO - 2017-05-14 22:11:57 --&gt; URI Class Initialized
  DEBUG - 2017-05-14 22:11:57 --&gt; No URI present. Default controller set.
  INFO - 2017-05-14 22:11:57 --&gt; Router Class Initialized
  INFO - 2017-05-14 22:11:57 --&gt; Output Class Initialized
  INFO - 2017-05-14 22:11:57 --&gt; Security Class Initialized
  DEBUG - 2017-05-14 22:11:57 --&gt; Global POST, GET and COOKIE data sanitized
  INFO - 2017-05-14 22:11:57 --&gt; CSRF cookie sent
  INFO - 2017-05-14 22:11:57 --&gt; Input Class Initialized
  INFO - 2017-05-14 22:11:57 --&gt; Language Class Initialized
  INFO - 2017-05-14 22:11:57 --&gt; Loader Class Initialized
  </code></pre>