ubuntu public key is not available: NO_PUBKEY

The following signatures couldn’t be verified because t…
nvoke-Success ‘if /usr/bin/test -w /var/lib/command-not-found/ -a -e /usr/lib/cnf-update-db; then /usr/lib/cnf-update-db > /dev/null; fi

nvoke-Success ‘if /usr/bin/test -w /var/lib/command-not…