I found a weird "bug" in pfblockerng
If you have pfblockerng installed with DNSBL enabled, and only use unbound as your firewall's only DNS server, you can't complete a reboot after configuration restore.
Netgate support confirmed the issue.
This is essentially what happens:
You wipe the machine, and install with a new image.
Configure it enough to do a configuration restore.
The configuration detects that you have missing packages, and tries to download them.
This makes a DNS request to unbound.
Unbound can't start because the configuration file includes a custom line to load pfblockerng blocked entries, which don't exist, because the package isn't installed yet.
As unbound can't load, you can't complete the dns request necessary to download and install packages, including pfblockerng, which means that a circular dependency occurs.
The escape strategy is to load the webui, and change the DNS entries the firewall is using, and disabling unbound.
Perhaps a warning message needs to be made while using only 127.0.0.1 as dns, while using dnsbl.
See the following redmine:
Until this is fixed in Unbound, you should either disable DNSBL before making a backup, or run the following command to temporarily create the file:
Thank you for your fast reply, and good information.