phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 2

INSERT INTO phpbb2_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('e7e0c40cc4ea8e0c6c36e05a3d2efcec', -1, 1548112818, 1548112818, '3457fdca', 0, 0, 0)

Line : 172
File : sessions.php