Fatal error: Uncaught PDOException: SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'fk_user' cannot be null in /var/www/html/logout.php:6 Stack trace: #0 /var/www/html/logout.php(6): PDOStatement->execute(Array) #1 {main} thrown in /var/www/html/logout.php on line 6