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 ('6bdf9e31f90fd4f3dc21026c37f50bf2', -1, 1413937361, 1413937361, '36ccf9b8', -1, 0, 0)

Line : 189
File : sessions.php