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 ('e9879b3cc65271fc5f5c48283cdf38a8', -1, 1413888014, 1413888014, '365a998d', -16, 0, 0)

Line : 189
File : sessions.php