Error Message:
DataTables warning: table id=all-queries - Tried 100 times to connect to FTL server, but never got proper reply. Please check Port and logs!
Resolution:

Case Standalone Linux OS Installation:

sudo service pihole-FTL stop
sudo mv /etc/pihole/pihole-FTL.db/etc/pihole/pihole-FTL-damaged.db
sudo service pihole-FTL start

Case Kubernetes Cluster:

k scale deployment --replicas=0 pihole
# wait a few seconds for existing pods to terminate
sudo mv /mnt/pathToNfsPihole/pihole-FTL.db /mnt/pathToNfsPihole/pihole-FTL.db.bad
k scale deployment --replicas=1 pihole