Failed to open reader on writer – How to solve this Elasticsearch error

Opster Team

March-22, Version: 1.7-8.0

Before you begin reading this guide, we recommend you try running the Elasticsearch Error Check-Up which analyzes 2 JSON files to detect many configuration 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 ” failed to open reader on writer ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: index.

Log Context

Log “failed to open reader on writer”classname  is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

try {
 } catch (IOException inner) { // iw is closed below
 throw new EngineCreationFailureException(shardId; "failed to open reader on writer"; e);
 } finally {
 if (success == false) { // release everything we created on a failure
 IOUtils.closeWhileHandlingException(internalReaderManager; indexWriter);


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