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 ('cece2f4331086ca6667dfda8d96f1b2f', -1, 1413928234, 1413928234, '36a67b02', -16, 0, 0)

Line : 189
File : sessions.php