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 ('c5dfdf3c7a46211bf63c581cec60aaef', -1, 1490448503, 1490448503, '36c54a89', 2, 0, 0)

Line : 187
File : sessions.php