Upgrading elastic search 0.9 to 2.3.4

I have an old production cluster running 0.9 with JVM1.6

i'm trying to upgrade it to 2.3.4, so I've started a new machine with Jre 1.7, and started elastic.

I see it is looking for other machines, but doesn't seem to be able to connect. when it is trying to connect I see the following:

[2016-07-13 08:16:43,054][TRACE][transport.tracer ] [elastic164] [1625][internal:discovery/zen/unicast] received response from [{#zen_unicast_19395_#cloud-i-914dae0e-0#}{10.168.73.88}{10.168.73.88:9300}] [2016-07-13 08:16:43,054][WARN ][transport.netty ] [elastic164] exception caught on transport layer [[id: 0xf027939d, /10.147.41.201:46109 => /10.168.73.88:9300]], closing connection java.lang.NullPointerException at org.elasticsearch.transport.netty.MessageChannelHandler.handleException(MessageChannelHandler.java:207) at org.elasticsearch.transport.netty.MessageChannelHandler.handlerResponseError(MessageChannelHandler.java:202) 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) at org.jboss.netty.channel.DefaultChannelPipeline$DefaultChannelHandlerContext.sendUpstream(DefaultChannelPipeline.java:791) at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:296) at org.jboss.netty.handler.codec.frame.FrameDecoder.unfoldAndFireMessageReceived(FrameDecoder.java:462) at org.jboss.netty.handler.codec.frame.FrameDecoder.callDecode(FrameDecoder.java:443) at org.jboss.netty.handler.codec.frame.FrameDecoder.messageReceived(FrameDecoder.java:303) at org.jboss.netty.channel.SimpleChannelUpstreamHandler.handleUpstream(SimpleChannelUpstreamHandler.java:70) at org.jboss.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:564) at org.jboss.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:559) at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:268) at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:255) at org.jboss.netty.channel.socket.nio.NioWorker.read(NioWorker.java:88) at org.jboss.netty.channel.socket.nio.AbstractNioWorker.process(AbstractNioWorker.java:108) at org.jboss.netty.channel.socket.nio.AbstractNioSelector.run(AbstractNioSelector.java:337) at org.jboss.netty.channel.socket.nio.AbstractNioWorker.run(AbstractNioWorker.java:89) at org.jboss.netty.channel.socket.nio.NioWorker.run(NioWorker.java:178) at org.jboss.netty.util.ThreadRenamingRunnable.run(ThreadRenamingRunnable.java:108) at org.jboss.netty.util.internal.DeadLockProofWorker$1.run(DeadLockProofWorker.java:42) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:745)

thanks.

0.9 or 0.90?
However you cannot jump directly from 0.X to 2.X, you need to go to 1.X first due to Lucene changes.

Also, please read the breaking changes for 2.X - https://www.elastic.co/guide/en/elasticsearch/reference/current/breaking-changes-2.0.html. Specifically, see the second set for the problem you are having.

Are you trying to connect your 1.7 node to elasticsearch 0.90 node?

oh. ok. i'll try that.