Exception in thread "main" **UnavailableException()**

> 
> at
>  org.apache.cassandra.thrift.Cassandra$batch\_mutate\_result.read(Cassandra.java:16485)
>  at
>  org.apache.cassandra.thrift.Cassandra$Client.recv\_batch\_mutate(Cassandra.java:916)
>  at
>  org.apache.cassandra.thrift.Cassandra$Client.batch\_mutate(Cassandra.java:890)
>  at WordCountSetup.main(Unknown
>  Source)
> 
> 
> 

Hi, I got this error while running a job in cassandra. can anyone help me how to get those class files.
thanks in advance..