Session: Error while trying to free lock for ci_session

In any controller method after you're finished writing session data. You can still get session data after you've called session_write_close but you can't modify it.

Code:

<?php if ( !defined( 'BASEPATH' ) ) exit( 'No direct script access allowed' );

class Welcome extends CI_Controller {
    public function index( ) {

        // code that modifies session data

        session_write_close( );

        $this->load->view( 'welcome_message' );
    }
}