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 ('744887a89f9f2625213e24f4384f6d72', -1, 1397917717, 1397917717, '36ea3c85', 7, 0)

Line : 170
File : sessions.php