exception caught on transport layer – 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 an exception is caught on the transport layer of Elasticsearch. The cause of this error can vary, and it may require further investigation to identify the root cause. However, some common causes include network connectivity issues or a node that is overloaded. To resolve the issue, you should investigate the root cause of the error and take appropriate action to fix the problem.

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 ” exception caught on transport layer ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: netty.

Log Context

Log “exception caught on transport layer [{}]; closing connection” classname is NettyTransport.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

        } else {
            logger.warn("exception caught on transport layer [{}]; closing connection"; e.getCause(); ctx.getChannel());
            // close the channel; which will cause a node to be disconnected if relevant
            disconnectFromNodeChannel(ctx.getChannel(); e.getCause());


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