Error closing netty event loop group – How to solve related issues

Opster Team

Jan-20, Version: 1.7-8.0

Before you begin reading this guide, we recommend you run Elasticsearch Error Check-Up which can resolve issues that cause many errors.

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.

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up to analyze Elasticsearch configuration and help resolve this error.

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

            clientBootstrap = null;


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