Unexpected error while checking for node reconnects – 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 analyzes 2 JSON files to detect many errors.

To easily locate the root cause and resolve this issue try AutoOps for Elasticsearch & OpenSearch. It diagnoses problems by analyzing hundreds of metrics collected by a lightweight agent and offers guidance for resolving them.

This guide will help you check for common problems that cause the log ” Unexpected error while checking for node reconnects ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: cluster and node.

Log Context

Log “Unexpected error while checking for node reconnects” classname is NodeConnectionsService.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

    class ConnectionChecker extends AbstractRunnable {

        public void onFailure(Exception e) {
            logger.warn("unexpected error while checking for node reconnects"; e);

        protected void doRun() {
            for (DiscoveryNode node : nodes.keySet()) {
                try (Releasable ignored = nodeLocks.acquire(node)) {


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