# io.netty.util.concurrent.MultithreadEventExecutorGroup.newChild

**URL:** https://discuss.elastic.co/t/io-netty-util-concurrent-multithreadeventexecutorgroup-newchild/80828
**Category:** Elasticsearch
**Created:** [March 31, 2017, 2:43pm UTC](https://discuss.elastic.co/t/io-netty-util-concurrent-multithreadeventexecutorgroup-newchild/80828 "2017-03-31T14:43:32Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![Aromadz](https://avatars.discourse-cdn.com/v4/letter/a/edb3f5/32.png) [@Aromadz](https://discuss.elastic.co/u/Aromadz)
#### Post date: [March 31, 2017, 2:43pm UTC](https://discuss.elastic.co/t/io-netty-util-concurrent-multithreadeventexecutorgroup-newchild/80828/1 "2017-03-31T14:43:32Z")

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Hi. I am getting following error if I use datastax(Cassandra driver) with Elasticsearch Transport client. Does this have to do with race conditons ? Could you please provide some advice, solutions or documentations ?  
java.lang.AbstractMethodError: io.netty.util.concurrent.MultithreadEventExecutorGroup.newChild(Ljava/util/concurrent/Executor;[Ljava/lang/Object;)Lio/netty/util/concurrent/EventExecutor

Thanks in advance.

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### Author: ![jasontedor](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jasontedor/32/66992_2.png) [@jasontedor](https://discuss.elastic.co/u/jasontedor)
#### Post date: [April 1, 2017, 7:19pm UTC](https://discuss.elastic.co/t/io-netty-util-concurrent-multithreadeventexecutorgroup-newchild/80828/2 "2017-04-01T19:19:35Z")

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I think you have conflicting versions of Netty, namely at least a version different than the Elasticsearch client expects or the Cassandra client expects.

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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: [April 4, 2017, 7:19pm UTC](https://discuss.elastic.co/t/io-netty-util-concurrent-multithreadeventexecutorgroup-newchild/80828/3 "2017-04-04T19:19:57Z")

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