title: Code Igniter blank page with no error display even though display errors are on
body: <p>I am using CodeIgniter 2.1.4 version. My production server environment is "PHP Version 5.5.26-1+deb.sury.org~precise+1", Apache, Ubuntun.</p>
  
  <p>Display error is on server wide. I've turned it on from the index.php like following code as well</p>
  
  <pre><code>if (defined('ENVIRONMENT'))
  {
      switch (ENVIRONMENT)
      {
          case 'development':
              error_reporting(E_ALL ^ (E_NOTICE | E_WARNING | E_DEPRECATED));
              ini_set('display_errors', 1);
          break;
  
          case 'testing':
          case 'production':
              error_reporting(E_ALL ^ (E_NOTICE | E_WARNING | E_DEPRECATED));
              ini_set('display_errors', 1);
          break;
  
          default:
              exit('The application environment is not set correctly.');
      }
  }
  </code></pre>
  
  <p>Apache error.log</p>
  
  <pre><code>[Thu Jul 09 06:25:10.623268 2015] [mpm_prefork:notice] [pid 5000] AH00163: Apache/2.4.12 (Ubuntu) OpenSSL/1.0.1 configured -- resuming normal operations
  [Thu Jul 09 06:25:10.623313 2015] [core:notice] [pid 5000] AH00094: Command line: '/usr/sbin/apache2'
  [Thu Jul 09 11:18:37.211428 2015] [mpm_prefork:notice] [pid 5000] AH00169: caught SIGTERM, shutting down
  [Thu Jul 09 11:18:38.742472 2015] [mpm_prefork:notice] [pid 29818] AH00163: Apache/2.4.12 (Ubuntu) OpenSSL/1.0.1 configured -- resuming normal operations
  [Thu Jul 09 11:18:38.742552 2015] [core:notice] [pid 29818] AH00094: Command line: '/usr/sbin/apache2'
  [Thu Jul 09 12:11:37.699200 2015] [mpm_prefork:notice] [pid 29818] AH00169: caught SIGTERM, shutting down
  [Thu Jul 09 12:11:38.517693 2015] [mpm_prefork:notice] [pid 3072] AH00163: Apache/2.4.12 (Ubuntu) OpenSSL/1.0.1 configured -- resuming normal operations
  [Thu Jul 09 12:11:38.517797 2015] [core:notice] [pid 3072] AH00094: Command line: '/usr/sbin/apache2'
  [Thu Jul 09 12:19:15.599384 2015] [mpm_prefork:notice] [pid 3072] AH00169: caught SIGTERM, shutting down
  [Thu Jul 09 12:19:16.423490 2015] [mpm_prefork:notice] [pid 3819] AH00163: Apache/2.4.12 (Ubuntu) OpenSSL/1.0.1 configured -- resuming normal operations
  [Thu Jul 09 12:19:16.423584 2015] [core:notice] [pid 3819] AH00094: Command line: '/usr/sbin/apache2'
  </code></pre>
  
  <p>Except this, there's nothing in there. And I don't think it's related.</p>
  
  <p>But no errors were shown and totally blank page. It's running fine on other production server environment as well as localhost. </p>
  
  <p>What should I check and how should I resolve it?</p>
  
  <p>Thank you.</p>