phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' 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 ('e0def54d418a30fe4b40558b9a1c5e26', -1, 1540257322, 1540257322, '36a2766b', 0, 0, 0)

Line : 187
File : sessions.php