Failed to send failed shard to – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 2.3-2.3

Briefly, this error occurs when Elasticsearch is unable to communicate with a node to which it is trying to send a shard due to network issues, node failure, or cluster misconfiguration. To resolve this, you can check the network connectivity between the nodes, ensure that the node is up and running, and verify the cluster configuration. If the issue persists, you may need to manually reassign the shard to a different node or consider increasing the cluster’s resilience by adding more nodes.

This guide will help you check for common problems that cause the log ” failed to send failed shard to {} ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: cluster and shard.

Log Context

Log “failed to send failed shard to {}” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

         ShardRoutingEntry shardRoutingEntry = new ShardRoutingEntry(shardRouting; indexUUID; message; failure);
                SHARD_FAILED_ACTION_NAME; shardRoutingEntry; new EmptyTransportResponseHandler(ThreadPool.Names.SAME) {
                    public void handleException(TransportException exp) {
                        logger.warn("failed to send failed shard to {}"; exp; masterNode);

    public void shardStarted(final ShardRouting shardRouting; String indexUUID; final String reason) {


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