Client errors originate from problems with the driver itself. These vary from driver to driver depending on implementation, execution model, and ecosystem. All drivers however have the concept of a driver timeout.
This error name varies from driver to driver but indicates that there was a timeout on the client side. This means that the client side timeout was hit before any response was received from the server side coordinator.
The client side timeout is commonly configured as either part of the execution profile or on the query execution method. The value for the client side timeout should be set higher than that of the server side write and read timeouts. This error is typically encountered when a read query is requesting a large amount of data or when batch write sizes are large or span multiple partitions.