Pi-Hole DNS Fails to Start - Solution
My system was having issues after the update script finished and piihole-FTL (DNS) would not start. After much research I was pointed to trying the latest init script. That fixed it for me.
Replace the current one in
sudosystemctldaemon-reload sudosystemctldisablepihole-FTL.service sudosystemctlenablepihole-FTL.service sudosytemctlstartpihole-FTL.service
That should get it working again.
You may need to override
/etc/resolv.conf initially to reach anywhere external. Restore it after you fix the service.