Okay, I was able to address my problem from the thread here:
The solution was to temporarily change nameserver in /etc/resolv.conf from 127.0.0.1 to 8.8.8.8 :
sudo sed -i 's/127.0.0.1/8.8.8.8/' /etc/resolv.conf
And run repair:
pihole -r
Here are the failures:
[✗] Backing up index.lighttpd.html
No default index.lighttpd.html file found... not backing up
[✗] DNS service is NOT running
After a pihole restartdns and pihole status I see:
[✓] DNS service is running
[✓] Pi-hole blocking is Enabled
However, I'm still not able to access the dashboard at http://PIHOLE-IPADDRESS/admin/
I suspect lighttpd is to blame.
sudo service lighttpd start
Job for lighttpd.service failed because the control process exited with error code.
See "systemctl status lighttpd.service" and "journalctl -xe" for details.
systemctl status lighttpd.service
● lighttpd.service - Lighttpd Daemon
Loaded: loaded (/lib/systemd/system/lighttpd.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Wed 2019-06-26 01:51:31 BST; 2min 4s ago
Process: 13777 ExecStartPre=/usr/sbin/lighttpd -tt -f /etc/lighttpd/lighttpd.conf (code=exited, status=255/EXCEPTION)
Jun 26 01:51:31 raspberrypi systemd[1]: lighttpd.service: Service RestartSec=100ms expired, scheduling restart.
Jun 26 01:51:31 raspberrypi systemd[1]: lighttpd.service: Scheduled restart job, restart counter is at 5.
Jun 26 01:51:31 raspberrypi systemd[1]: Stopped Lighttpd Daemon.
Jun 26 01:51:31 raspberrypi systemd[1]: lighttpd.service: Start request repeated too quickly.
Jun 26 01:51:31 raspberrypi systemd[1]: lighttpd.service: Failed with result 'exit-code'.
Jun 26 01:51:31 raspberrypi systemd[1]: Failed to start Lighttpd Daemon.