# Java transport client do not work after upgrade to 6.5.3

**URL:** <https://discuss.elastic.co/t/java-transport-client-do-not-work-after-upgrade-to-6-5-3/161726>\
**Category:** Elasticsearch\
**Created:** [December 20, 2018, 4:04pm UTC](https://discuss.elastic.co/t/java-transport-client-do-not-work-after-upgrade-to-6-5-3/161726 "2018-12-20T16:04:36Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![DavidTurner](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/davidturner/32/22453_2.png) [@DavidTurner](https://discuss.elastic.co/u/DavidTurner)\
**Post date:** [December 23, 2018, 9:50am UTC](https://discuss.elastic.co/t/java-transport-client-do-not-work-after-upgrade-to-6-5-3/161726/3 "2018-12-23T09:50:11Z")

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> [@ivanqwam](#):
>
> java.lang.IllegalArgumentException: NamedWriteable [org.elasticsearch.cluster.NamedDiff][persistent\_tasks] is already registered for [org.elasticsearch.cluster.ClusterModule$$Lambda$777/506775047], cannot register [org.elasticsearch.xpack.core.XPackClientPlugin$$Lambda$784/402207819]

I think you have a stale dependency somewhere within your client. In 6.3+, `XPackClientPlugin` does not try and register a `persistent_tasks` named writeable, but it did in 6.2.

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