Laravel HTTP ERROR 500

In my server (CentOS 7), one of my Laravel 5 projects(the other projects work fine) is not working and returns HTTP ERROR 500.
I have all permissions for storage folder and everything is well, but this error is always diplayed
Version used for Laravel is 5.1 and web server httpd
I took a deep look the other similar questions but nothing helps.
any suggestion please?
Thanks alot

via Chebli Mohamed