如何在codeigniter中显示错误而不是HTTP ERROR 500

My CI project doesnt show any error and it is only show HTTP ERROR 500.
I have searched already and done these:

define('ENVIRONMENT', 'development');

    case 'development':
    error_reporting(E_ALL);
    ini_set('display_errors', 'On');
    ini_set("error_reporting","E_ALL & ~E_NOTICE & ~E_STRICT");
    break;

Also tested

ini_set('display_errors', 1);

But nothing changed.
Any help would be apriciated.

I have encountered this problem before. this problem occurs because I deleted the errors folder inapplication / view codeigniter.

the solution is only to download the folder back on the codeigniter web