At a time ago I set up a VPS with Cpanel and I had this same problem, however I remember where it was changed but I can not remember the line of php.ini
The problem is that I have a page that the user enters with a login and a password, in this page if $_SESSION is not in the parameters, it shows this line
session_destroy();
header("Location: logar.php"); exit;
But it does not redirect or show any error in LOG .
Someone can give me a light, I'm sure it was in php.ini , but this is already a couple of years, and now I'm needing it again.