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 ('f0e9440184fba80e26e16543e324deeb', -1, 1397908565, 1397908565, '36d31b3d', 7, 0)

Line : 170
File : sessions.php