TeleTet : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'session_user_id'

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('af9c58d10d9f0b1c998a4e42b861e453', -1, 1413828878, 1413828878, '3653a798', -16, 0, 0)

Line : 189
File : sessions.php