503 response in Laravel since composer update

since i did my last composer update, i always get an 503(Service Unavailable) when i do a dd(), die or exit. Are there any known issues? Google couldn't bring the answer.

I'm using Laravel 5.1, my last composer package was "barryvdh/laravel-dompdf" github

Thank you for your help.

Best regards,

Marco

via Chebli Mohamed