title: CodeIgniter 3.1.7 - Class 'MY_Controller' not found error occurred only on my server
body: <p>I got the following error:</p>
  
  <blockquote>
    <p>Fatal error: Class 'MY_Controller' not found in
    /www/panel/application/controllers/Posts.php on line 3</p>
    
    <p>A PHP Error was encountered Severity: Error</p>
    
    <p>Message: Class 'MY_Controller' not found</p>
    
    <p>Filename: controllers/Posts.php</p>
    
    <p>Line Number: 3</p>
    
    <p>Backtrace:</p>
  </blockquote>
  
  <p>subclass_prefix config is:</p>
  
  <pre><code>$config['subclass_prefix'] = 'MY_';
  </code></pre>
  
  <p>MY_Controller.php is placed on application/core with the filename correctly spelled: MY_Controller.php</p>
  
  <p>I didn't have this problem when I was developing the site on localhost. This error only occurred on my server.</p>
  
  <p>I have tried to google for solution but I didn't find anything helpful. </p>
  
  <p>What can it went wrong? Thanks a lot in advance.</p>