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 ('08a8a5b7be2b8f563c60ad07d641cb96', -1, 1406938945, 1406938945, '36cd8928', 7, 0)

Line : 170
File : sessions.php