phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'session_user_id'

INSERT INTO forum_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('82d61c6a601227d52e244ad3d0e49ec7', -1, 1540120724, 1540120724, '36a174e1', 5, 0, 0)

Line : 187
File : sessions.php