I encountered this problem again, so let’s write it down to avoid googling it.

Problem:

PowerDNS fails to start with
pdns.service: Failed at step ADDRESS_FAMILIES spawning /usr/sbin/pdns_server: Invalid argument


Solution:

1. edit /lib/systemd/system/pdns.service
2. comment out RestrictAddressFamilies
3. comment out ProtectSystem=full
4. possibly kill systemd-resolved
5. systemctl daemon-reload
6. ask yourself again, why are you using debian with systemd on server ? And why the hell it is starting services I’ve never configured to start ? Isn’t it time to switch to windows ? It seems more predictable to me…