Marking unavailable shards as stale – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 6.8-8.9

Briefly, this error occurs when Elasticsearch cannot access certain shards due to issues like node failures, network problems, or disk errors. The system marks these unavailable shards as stale to prevent data inconsistency. To resolve this, you can try restarting the Elasticsearch node, checking your network connections, or inspecting your disk for errors. If the problem persists, consider reallocating the shards or increasing the cluster’s resilience by adding more nodes.

To mark unavailable shards as stale, we recommend you run the Elasticsearch Error Check-Up. It’ll check all of the shards in your system and assist you in implementing any changes needed.

This guide will help you check for common problems that cause the log “marking unavailable shards as stale” 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, index, routing and shards.

Log Context

Log “{} marking unavailable shards as stale: {}” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

                    if (indexMetadataBuilder == null) {
                        indexMetadataBuilder = IndexMetadata.builder(oldIndexMetadata);
                    indexMetadataBuilder.putInSyncAllocationIds(shardNumber; remainingInSyncAllocations);
                logger.warn("{} marking unavailable shards as stale: {}"; shardEntry.getKey(); idsToRemove);

            if (indexMetadataBuilder != null) {
                if (metadataBuilder == null) {
                    metadataBuilder = Metadata.builder(oldMetadata);


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