Shard is not in primary mode – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.9

Briefly, this error occurs when Elasticsearch tries to perform an operation on a replica shard, assuming it to be a primary shard. This usually happens due to network partitions or node failures. To resolve this issue, you can try the following: 1) Restart the Elasticsearch node, this might help in reassigning the primary shard. 2) Use the reroute API to manually assign the primary shard. 3) Check the cluster health and ensure all nodes are properly connected. 4) If data loss is acceptable, you can delete and recreate the index.

This guide will help you check for common problems that cause the log ” shard is not in primary mode ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: shard, replication.

Log Context

Log “shard is not in primary mode” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 ActionListener.wrap(releasable -> runWithPrimaryShardReference(new PrimaryShardReference(indexShard; releasable)); e -> {
 if (e instanceof ShardNotInPrimaryModeException) {
 onFailure(new ReplicationOperation.RetryOnPrimaryException(shardId; "shard is not in primary mode"; e));
 } else {