phpBB by Przemo : 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 ('dd761dc0387d8777d1e19aa7a58e6d5b', -1, 1540120398, 1540120398, '36a16418', 0, 0, 0)

Line : 445
File : sessions.php