In what scenarios might a user encounter the "Sie sind nicht eingeloggt" message when using PHP sessions for authentication?

The message "Sie sind nicht eingeloggt" (translated as "You are not logged in") typically appears when a user tries to access a restricted page without being authenticated through PHP sessions. To solve this issue, you need to ensure that the user is properly logged in before allowing access to restricted content by checking the session variables that store the user's authentication status.

session_start();

if (!isset($_SESSION['logged_in']) || $_SESSION['logged_in'] !== true) {
    header("Location: login.php");
    exit();
}