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 ('74d99e8f43f85ade5a52e42c2bb2ee6e', -1, 1414259468, 1414259468, '36594f21', -16, 0, 0)

Line : 189
File : sessions.php