phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('6e1ca5ecbdc773fbc588c7f9c258ece6', -1, 1506358273, 1506358273, '3651585d', -2, 0, 0)

Line : 187
File : sessions.php