Philips Hue bulbs no longer working and getting NoAvailableHostsException

To the best of my knowledge, this is a Cassandra Database error (cloud database).

It means there’s either a temporary operational issue in the cloud (too many connections, too bus, …) or some bug that has caused a bad database query (e.g., accidentally selecting way too many records unbounded).

SmartThings ought to trap these errors and make them read more friendly, but Tech Support will help.