Updating number-of-replicas to for indices – 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 can resolve issues that cause many errors.

This guide will help you check for common problems that cause the log ” Updating number-of-replicas to for indices ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: cluster, indices, metadata and settings.

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up to analyze Elasticsearch configuration and help resolve this error.

Log Context

Log “updating number_of_replicas to [{}] for indices {}” classname is MetaDataUpdateSettingsService.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

                int updatedNumberOfReplicas = openSettings.getAsInt(IndexMetaData.SETTING_NUMBER_OF_REPLICAS; -1);
                if (updatedNumberOfReplicas != -1) {
                    routingTableBuilder.updateNumberOfReplicas(updatedNumberOfReplicas; actualIndices);
                    metaDataBuilder.updateNumberOfReplicas(updatedNumberOfReplicas; actualIndices);
                    logger.info("updating number_of_replicas to [{}] for indices {}"; updatedNumberOfReplicas; actualIndices);

                ClusterBlocks.Builder blocks = ClusterBlocks.builder().blocks(currentState.blocks());
                Boolean updatedReadOnly = openSettings.getAsBoolean(IndexMetaData.SETTING_READ_ONLY; null);
                if (updatedReadOnly != null) {


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