Fail to auto expand replicas to – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 2.3-2.3

Briefly, this error occurs when Elasticsearch tries to automatically expand the number of replicas based on the cluster’s configuration but fails. This could be due to insufficient nodes, disk space, or other resource limitations. To resolve this issue, you can manually set the number of replicas, ensure there are enough nodes in the cluster, or check if there’s enough disk space. Also, consider adjusting the auto-expand replicas setting in your index settings if it’s causing frequent issues.

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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