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 ('04a972f7d80d3b71116186fe7f4c1729', -1, 1545169838, 1545169838, '340646ca', 2, 0, 0)

Line : 187
File : sessions.php