indexfiliere:1 GET http://localhost:8888/samanelms/Filiere/indexfiliere 500 (Internal Server Error) strip doctrine php

Question

I use doctrine in php. Each time if try to retrieve the information in the database for a select request. the request will not be executed and it generates a browser error

with the source code

public function getListeOfFiliere(){
  if($this->db == null) return ;
  return $this->db->getRepository("Filiere")->findAll();
}

and the database configuration:

$orm = array('dbname' => 'dbname', 'user'     => 'user','port' =>'port','password' => 'password','host' => 'localhost','driver' => 'pdo_mysql');