phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'session_user_id'

INSERT INTO forums_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in) VALUES ('1f4d27305be795b944b223b59bb49561', -1, 1414030668, 1414030668, '00000000', 0, 0)

Line : 133
File : /home/naija/public_html/Forums/includes/sessions.php