Fail to auto expand replicas to – 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 message indicates that Elasticsearch failed to automatically create replicas for a particular index. This could be due to various reasons such as insufficient disk space, network issues, or a misconfiguration of the Elasticsearch cluster. To resolve this issue, you can try increasing the disk space, checking the network connectivity, or adjusting the cluster settings to allow for more replicas.

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 ” Fail to auto expand replicas to ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: cluster, metadata and settings.

Log Context

Log “[{}] fail to auto expand replicas to [{}]” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :


                    public void onFailure(Throwable t) {
                        for (String index : indices) {
                            logger.warn("[{}] fail to auto expand replicas to [{}]"; index; fNumberOfReplicas);


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