Encountered this on Ubuntu 20.04 as well, workaround was to change to iptable-legacy and attempt stacking again.
apt-get update apt-get upgrade apt-get install iptable apt-get install arptables apt-get install ebtablesupdate-alternatives --set iptables /usr/sbin/iptables-legacy || true update-alternatives --set ip6tables /usr/sbin/ip6tables-legacy || true update-alternatives --set arptables /usr/sbin/arptables-legacy || true update-alternatives --set ebtables /usr/sbin/ebtables-legacy || true
Encountered this on Ubuntu 20.04 as well, workaround was to change to iptable-legacy and attempt stacking again.
apt-get update alternatives --set iptables /usr/sbin/ iptables- legacy || true ip6tables- legacy || true arptables- legacy || true ebtables- legacy || true
apt-get upgrade
apt-get install iptable
apt-get install arptables
apt-get install ebtablesupdate-
update-alternatives --set ip6tables /usr/sbin/
update-alternatives --set arptables /usr/sbin/
update-alternatives --set ebtables /usr/sbin/