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 ('77597e5957b602d5f480440180fd1c2b', -1, 1548028643, 1548028643, '22cbf54c', 3, 0, 0)

Line : 172
File : sessions.php