We also are autoloading various resources such as support for database access and session management. We need to specify that we're using these resources.

Open the autoload.php file from /path/to/codeigniter/application/config/ in your text editor and find the following line:

$autoload['libraries'] = array();

Replace this line with the following:

$autoload['libraries'] = array('database', 'session');

This will ensure that the resources that are required in order to access the database and to manage sessions are always with us.