pid is null when we try to run scheduler

[nabdali]

When I try to launch : php app/console scheduler:run I have this error

  [Doctrine\DBAL\Exception\NotNullConstraintViolationException]                                                                                                                                           
  An exception occurred while executing 'INSERT INTO task_queue (pid, name, created, updated, params, execute_at, started, finished, result, progress, progress_info, status, resolution, schedule_id) V  
  ALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)' with params [null, "glooby_task.pingg", "2018-02-20 11:14:54", "2018-02-20 11:14:54", "[]", "2018-02-20 11:13:00", null, null, null, null, null, "qu  
  eued", "queued", 3]:                                                                                                                                                                                    
                                                                                                                                                                                                          
  SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'pid' cannot be null    

unlike when launch app/console task:run glooby_task.ping is work succefully