Elastic Search Transport Client(6.8.23) not able to connect to ES 7.17.10

Elastic Stack Elasticsearch
,
1

Hi Team
My application is using the Elastic Search Transport Client(6.8.23) and am trying to connect to an Elasticsearch server which is 7.17.10 version. And am getting the below exception.

Caused by: NoNodeAvailableException[None of the configured nodes are available: [{#transport#-1}{NNvRVPQ1Qpan_KKOO5xRCw}{10.5.13.93:31400}]]
	at org.elasticsearch.client.transport.TransportClientNodesService.execute(TransportClientNodesService.java:250)

The cluster is in green state

{
  "name" : "elasticsearch-data-0",
  "cluster_name" : "elasticsearch-data-cluster",
  "cluster_uuid" : "Kc9N2jqyRxCZORw2VbZdPw",
  "version" : {
    "number" : "7.17.10",
    "build_flavor" : "default",
    "build_type" : "docker",
    "build_hash" : "fecd68e3150eda0c307ab9a9d7557f5d5fd71349",
    "build_date" : "2023-04-23T05:33:18.138275597Z",
    "build_snapshot" : false,
    "lucene_version" : "8.11.1",
    "minimum_wire_compatibility_version" : "6.8.0",
    "minimum_index_compatibility_version" : "6.0.0-beta1"
  },
  "tagline" : "You Know, for Search"
}```

Can someone please help to understand the issue .
2

It can not work. You must use the same versions. But some other things are wrong anyway:

You must upgrade to 7.17.10 and not a buggy version
Or better to 8.8.1
You need to switch to the new Java client.

3

yes thats the plan .. but ideally the libraries are forward compatible right .. even the official documentation says library upgrade as the last step during ES migration .

4

No. Not within major versions, and specifically with the removed TransportClient.

5

Sorry for asking it again. As per this documentation : Transport Client | Java Transport Client (deprecated) [7.17] | Elastic
Transport client is not getting removed as part of 7.17 , its getting deprecated right .. so ideally i should be able to access 7.17 using the 6.18 transport client libs right

6

No. I don't think this will work. If you want to access a 6.8 cluster, use a 6.8 TransportClient.
If you want to access a 7.17 cluster, use a 7.17 TransportClient. Although I recommend using the new Java client.