Delayed reroute reason failed – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 7.3-8.9

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Briefly, this error occurs when Elasticsearch attempts to reroute shards but fails due to issues like network problems, node failures, or insufficient resources. To resolve this, you can try the following: 1) Check the cluster’s health and ensure all nodes are functioning properly. 2) Verify network connectivity between nodes. 3) Ensure there’s enough disk space and memory available for Elasticsearch to operate. 4) Review Elasticsearch logs for more detailed error information. 5) If the issue persists, consider increasing the cluster’s capacity or optimizing your index settings to reduce resource usage.

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This guide will help you check for common problems that cause the log ” delayed reroute [” + reason + “] failed ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: routing, cluster.

Log Context

Log “delayed reroute [” + reason + “] failed” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 () -> format("unexpected failure during [%s]; current state version [%s]"; source; state.version());
 ActionListener.onFailure(currentListeners; new ElasticsearchException("delayed reroute [" + reason + "] failed"; e));
 }  @Override
 public void clusterStateProcessed(ClusterState oldState; ClusterState newState) {
 future.addListener(ActionListener.running(() -> ActionListener.onResponse(currentListeners; null)));


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