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 ('d40a78ea17bb82c7dcfc0c15ac020f8c', -1, 1534470360, 1534470360, '36e137ae', 75, 0, 0)

Line : 187
File : sessions.php