phpBB : 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 ('df25723a5da6d899f4ec9cc0480f400d', -1, 1566098646, 1566098646, '12ce0d27', -9, 0, 0)

Line : 172
File : /home/rebkell/public_html/boards/includes/sessions.php