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 ('ed81de6ad1b29882a8cc707ac22cd918', -1, 1398082829, 1398082829, '6b162d3d', 7, 0)

Line : 170
File : sessions.php