Failing snapshot of shard on unassigned shard – How to solve this OpenSearch error

Opster Team

Aug-23, Version: 1-2.9

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Briefly, this error occurs when OpenSearch attempts to create a snapshot of a shard that is currently unassigned. This could be due to a node failure, network issues, or disk space problems. To resolve this, you can try to manually reassign the shard if it’s due to a temporary issue. If it’s a persistent issue, consider checking your cluster health and addressing any underlying problems such as insufficient disk space or network connectivity issues. Additionally, ensure your snapshot repository is correctly configured and accessible.

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This guide will help you check for common problems that cause the log ” failing snapshot of shard [{}] on unassigned shard [{}] ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: snapshot, shard.

Log Context

Log “failing snapshot of shard [{}] on unassigned shard [{}]” classname is
We extracted the following from OpenSearch source code for those seeking an in-depth context :

                // Shard that we were waiting for went into unassigned state or disappeared - giving up
                snapshotChanged = true;
                logger.warn("failing snapshot of shard [{}] on unassigned shard [{}]"; shardId; shardStatus.nodeId());
                final ShardSnapshotStatus failedState = new ShardSnapshotStatus(
                    "shard is unassigned";


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