# ES 1.6.2 Java client and ES 1.5.2 cluster

**URL:** <https://discuss.elastic.co/t/es-1-6-2-java-client-and-es-1-5-2-cluster/227999>\
**Category:** Elasticsearch\
**Created:** [April 14, 2020, 9:04pm UTC](https://discuss.elastic.co/t/es-1-6-2-java-client-and-es-1-5-2-cluster/227999 "2020-04-14T21:04:56Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Cleosson\_Souza](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/cleosson_souza/32/66321_2.png) [@Cleosson\_Souza](https://discuss.elastic.co/u/Cleosson_Souza)\
**Post date:** [April 14, 2020, 9:04pm UTC](https://discuss.elastic.co/t/es-1-6-2-java-client-and-es-1-5-2-cluster/227999/1 "2020-04-14T21:04:57Z")

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Hello,

I took a look at [end of life](https://www.elastic.co/support/eol) and I understood that ES 1.6.2 Java client is compatible with ES 1.5.2 cluster  
Is ES 1.6.2 Java client really compatible with ES 1.5.2 cluster ?  
Is that compatibility official ?

Thanks  
Cleosson

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**Author:** ![Luca\_Belluccini](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/luca_belluccini/32/33239_2.png) [@Luca\_Belluccini](https://discuss.elastic.co/u/Luca_Belluccini)\
**Post date:** [April 15, 2020, 12:12am UTC](https://discuss.elastic.co/t/es-1-6-2-java-client-and-es-1-5-2-cluster/227999/2 "2020-04-15T00:12:22Z")

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Hello @Cleosson_Souza

The compatibility is usually showed in the [support matrix](https://www.elastic.co/support/matrix#matrix_jvm).

The EoL page shows until which version the product is maintained.

The official documentation for your client is [at this link](https://www.elastic.co/guide/en/elasticsearch/client/java-api/1.6/client.html).

**We strongly suggest to upgrade to a supported version of the Elastic Stack.**

As noted at [this page](https://www.elastic.co/guide/en/elasticsearch/client/java-api/1.6/client.html#client):

> Please note that you are encouraged to use the same version on client and cluster sides. You may hit some incompatibility issues when mixing major versions.

As far as I recall, ES 1.6 client was based on the transport protocol and the client was actually "joining" the cluster as a client node and the communication is in binary protocol.  
If the client node joins the cluster and receives the cluster state, it _should_ work. But it is not guaranteed.

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [May 13, 2020, 12:12am UTC](https://discuss.elastic.co/t/es-1-6-2-java-client-and-es-1-5-2-cluster/227999/3 "2020-05-13T00:12:23Z")

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