Connection failed to node at – How to solve related issues

Opster Team

Feb-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.

Briefly, this error occurs when Elasticsearch is unable to connect to a node in the cluster. This could be caused by a variety of reasons, including network issues, firewall settings, or an incorrect IP address or port. To resolve this issue, you can check the network connectivity between the nodes, ensure that the correct IP address and port are being used, and check any firewall or security settings that may be blocking the connection.

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 ” Connection failed to node at ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: node and plugin.

Log Context

Log “connection failed to node at [{}://{}:{}]” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :


    public void onFailure(final Node node) {
        HttpHost host = node.getHost();
        logger.warn("connection failed to node at [{}://{}:{}]"; host.getSchemeName(); host.getHostName(); host.getPort());

        final HttpResource resource = this.resource.get();
        final Sniffer sniffer = this.sniffer.get();

        if (resource != null) {


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