phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO mex2mex_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in) VALUES ('6d7db1c49bf3bda700a0c2d5f88283ee', -1, 1406557330, 1406557330, '36e338ae', 7, 0)

Line : 170
File : sessions.php