Unable to take database backup in Codeigniter 3

I want to take a backup of my database. My CodeIgniter version is 3.0.1 And when I run the code, it just load for some time and then just blanks out. My database size is greater than 60MB. Nothing happened. My code is given below.

    {
        
        
        
       
       // Load the DB utility class
    $this->load->database();
$this->load->dbutil();
     // $dbs = $this->dbutil->list_databases();
         

     $prefs = array(
            //'tables'      => array('hotel_accomodation'),  // Array of tables to backup.
            'ignore'      => array(),           // List of tables to omit from the backup
            'format'      => 'txt',             // gzip, zip, txt
            'filename'    => ''.date("Y-m-d-H-i-s").'-mybackup.sql',    // File name - NEEDED ONLY WITH ZIP FILES
            'add_drop'    => TRUE,              // Whether to add DROP TABLE statements to backup file
            'add_insert'  => TRUE,              // Whether to add INSERT data to backup file
            'newline'     => "\n"               // Newline character used in backup file
          );



   $backup = $this->dbutil->backup($prefs);

  //  print_r($backup);
   
  // die;
  // var_dump($backup);
    
        
    // Load the file helper and write the file to your server
        $this->load->helper('file');
        
        write_file(base_url().'download/mybackup.gz', $backup);//file directory ka issue lag ra hy mujhy is ki access ka ya kuch... ya phir database ka size zia
        
        // Load the download helper and send the file to your desktop
        $this->load->helper('download');
        force_download('mybackup.gz', $backup);
    } ```