phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '0' for key 'session_user_id'

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('7ab9d682930cd72ae2d075d9f9c96391', -1, 1534470421, 1534470421, '36e137ae', 75, 0, 0)

Line : 187
File : sessions.php