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 ('4a47f90656fcb6d196e326bacb79568a', -1, 1406961097, 1406961097, '36592e51', 7, 0)

Line : 170
File : sessions.php