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 ('a778ac321674bdbbe236a75ea0093cc9', -1, 1410953417, 1410953417, '00000000', 0, 0)

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