When running the upgrade the upgrade wizard is unreachable on port 8300 error 404 when reaching the upgrade wizard page.
port 8300 is being blocked by iptables/firewall
%sudo iptables -A INPUT -p tcp --dport 8300 -j ACCEPT
Rerun the upgrade wizard manually and browse to the upgrade page.
Once the upgrade is complete you can remove the iptables rule and restart the iptables service.