Rerouting shards: – How to solve related issues

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Rerouting shards: – How to solve related issues

Opster Team

Jan-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 ” Rerouting shards: ” to appear. It’s important to understand the issues related to the log, so to get started, read the general overview on common issues and tips related to the Elasticsearch concepts: allocation, cluster, monitor, routing and threshold.

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up which analyses ES to pinpoint the cause of many errors and provides suitable actionable recommendations how to resolve them (free tool that requires no installation).

Log Context

Log “Rerouting shards: [{}]” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

            if (reroute) {
      "rerouting shards: [{}]"; explanation);
            indicesToMarkReadOnly.removeIf(index -> state.getBlocks().indexBlocked(ClusterBlockLevel.WRITE; index));
            if (indicesToMarkReadOnly.isEmpty() == false) {


Run the Check-Up to get a customized report like this:

Analyze your cluster