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 ('5bb19c5ba50fb76dc0582698e45e5490', -1, 1414219220, 1414219220, '36a1cb17', -16, 0, 0)

Line : 189
File : sessions.php