elasticsearch client异常

WARN - NettyTransport.exceptionCaught(723) | [Korrek] exception caught on transport layer [[id: 0xf0dbd835, /192.168.1.113:60441 => /192.168.1.117:9300]], closing connection
java.lang.NullPointerException
at org.elasticsearch.transport.netty.MessageChannelHandler.handleException(MessageChannelHandler.java:206)
at org.elasticsearch.transport.netty.MessageChannelHandler.handlerResponseError(MessageChannelHandler.java:201)
at org.elasticsearch.transport.netty.MessageChannelHandler.messageReceived(MessageChannelHandler.java:136)
at org.jboss.netty.channel.SimpleChannelUpstreamHandler.handleUpstream(SimpleChannelUpstreamHandler.java:70)

at org.jboss.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:564)

解决方式：

1、java PAI和服务器的版本不一致

2、服务端没有关闭防火墙