amazon s3 php HTTP ERROR 500

use Awss3S3Client;
require dirname(__FILE__).'/vendor/autoload.php';
$config = require dirname(__FILE__).'/config.php';

On localhost it works well but in my remote hosting I'm getting HTTP ERROR 500.

I think the problem is in this part of the code:

$s3 = S3Client::factory([
    'key' => $config['s3'] ['key'],
    'secret' => $config['s3'] ['secret']
]);