iptables - Failed to start netfilter-persistent configuration - Ask Ubuntu

i'm using ubuntu 16.04 , until yesterday used ufw , had basic rules. need have more complex rules , decided use iptables (if understand right, can't have firewall rules in file without it). see error netfilter-persistance.service if run: sudo systemctl status netfilter-persistent.service

any idea?

first of check

sudo journalctl -e -u netfilter-persistent.service 

for errors. have @ rules being loaded netfilter-persistent service. located in /etc/iptables/rules.v4 , /etc/iptables/rules.v6. service pretty loads firewall rules using:

sudo iptables-restore < /etc/iptables/rules.v4 

you cat try debug line line (and same rules.v6). after removing erroneous statement can restart service:

sudo systemctl restart netfilter-persistent.service