Error closing netty event loop group – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 6.8-8.9

Briefly, this error occurs when Elasticsearch fails to close the Netty event loop group, which is responsible for handling network events. This could be due to a network issue, a bug in the software, or a system resource constraint. To resolve this issue, you can try restarting Elasticsearch, checking for any network issues, or upgrading Elasticsearch to the latest version. If the problem persists, consider increasing system resources or checking for any bugs in the software that might be causing this issue.

This guide will help you check for common problems that cause the log ” Error closing netty event loop group ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: netty.

Log Context

Log “Error closing netty event loop group” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

        protected void closeInternal() {
            Future> shutdownFuture = eventLoopGroup.shutdownGracefully(0; 5; TimeUnit.SECONDS);
            if (shutdownFuture.isSuccess() == false) {
                logger.warn("Error closing netty event loop group"; shutdownFuture.cause());



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