Adding index for shards were not acknowledged – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 8.9-8.9

Briefly, this error occurs when Elasticsearch is unable to acknowledge the addition of an index for shards, possibly due to a timeout or a network issue. To resolve this, you can increase the timeout period to allow more time for the operation to complete. Alternatively, check your network connection to ensure it’s stable and reliable. If the issue persists, consider reducing the number of shards or increasing the resources of your Elasticsearch cluster to improve its performance.

This guide will help you check for common problems that cause the log ” adding index [{}] for [{}]; shards were not acknowledged ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin, index, shards.

Log Context

Log “adding index [{}] for [{}]; shards were not acknowledged” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

                                "error adding index [{}] for [{}]; request was not acknowledged";
                        } else if (response.isShardsAcknowledged() == false) {
                            logger.warn("adding index [{}] for [{}]; shards were not acknowledged"; index; ClientHelper.PROFILING_ORIGIN);

                    public void onFailure(Exception e) {


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