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 ('3094e1168572f87a8d5bb61c6c5420dd', -1, 1398318452, 1398318452, '171414c3', 7, 0)

Line : 170
File : sessions.php