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 ('445cedf2a0443db4f68e94bedec8165c', -1, 1397972612, 1397972612, '36ccd7d1', 7, 0)

Line : 170
File : sessions.php