Ubuntu discontinued the use of /etc/network/interfaces a number of releases ago and in 19.10 have removed ifupdown. Please see the migrating to netplan document:
https://wiki.ubuntu.com/MigratingToNetplan
If you need to continue using /etc/network/interfaces then there are ways to install ifupdown and disable netplan.
I am closing this as invalid.
Ubuntu discontinued the use of /etc/network/ interfaces a number of releases ago and in 19.10 have removed ifupdown. Please see the migrating to netplan document:
https:/ /wiki.ubuntu. com/MigratingTo Netplan
If you need to continue using /etc/network/ interfaces then there are ways to install ifupdown and disable netplan.
I am closing this as invalid.