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 ('db3c81e9e962e6f604eb1946dd59e860', -1, 1414144360, 1414144360, '36a78a35', -16, 0, 0)

Line : 189
File : sessions.php