ClassNotFoundException: Attempted to load class "RuntimeException" from namespace "PHPThumb" in /var/www/.../vendor/dannytrue/phpthumb/src/PHPThumb/GD.php line 947. Do you need to "use" it from another namespace? Perhaps you need to add a use statement for one of the following: Symfony\Component\Intl\Exception\RuntimeException, Symfony\Component\DependencyInjection\Exception\RuntimeException, Symfony\Component\Yaml\Exception\RuntimeException, Symfony\Component\Form\Exception\RuntimeException, Symfony\Component\Process\Exception\RuntimeException, Symfony\Component\Serializer\Exception\RuntimeException, Symfony\Component\Security\Core\Exception\RuntimeException, Symfony\Component\Validator\Exception\RuntimeException, Symfony\Component\PropertyAccess\Exception\RuntimeException, Symfony\Component\Intl\Exception\RuntimeException, Gedmo\Exception\RuntimeException.