What are the potential reasons for the session_start() function not working in PHP 5?

The session_start() function may not work in PHP 5 due to incorrect session.save_path configuration, disabled session support, or headers already sent before calling session_start(). To solve this issue, ensure that the session.save_path is set correctly, enable session support in php.ini, and make sure there are no outputs before calling session_start().

<?php
// Check if session is not already started
if (session_status() == PHP_SESSION_NONE) {
    // Set the session save path
    session_save_path('/path/to/session/directory');
    
    // Enable session support
    session_start();
}
?>