Failed to send shard started to – How to solve related issues

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Failed to send shard started to – 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 ” Failed to send shard started to ” 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: cluster and shard.

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

         logger.debug("{} sending shard started for {}"; shardRoutingEntry.shardRouting.shardId(); shardRoutingEntry);
                SHARD_STARTED_ACTION_NAME; new ShardRoutingEntry(shardRouting; indexUUID; reason; null); new EmptyTransportResponseHandler(ThreadPool.Names.SAME) {
                    public void handleException(TransportException exp) {
                        logger.warn("failed to send shard started to [{}]"; exp; masterNode);



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

Analyze your cluster