Hosting with OpenShift RedHat get 500 errors when access the website

I have this website.The problem I have is

The freelancer-ngohungphuc.rhcloud.com page isn’t working

freelancer-ngohungphuc.rhcloud.com is currently unable to handle this request.

500

I develop this website using Laravel 5.1.So what I have to do to fix this error.

Thanks in advanced

via Chebli Mohamed