Failed to retrieve shard size for – How to solve this OpenSearch error

Opster Team

Aug-23, Version: 1-2.9

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Briefly, this error occurs when OpenSearch is unable to fetch the size of a specific shard. This could be due to network issues, insufficient permissions, or the shard may not exist. To resolve this, ensure the shard exists and is accessible. Check your network connectivity and verify that the user has the necessary permissions to access the shard. If the shard is corrupted or missing, it may need to be recreated or restored from a backup.

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

Log Context

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


        public void onFailure(Exception e) {
            logger.warn(() -> new ParameterizedMessage("failed to retrieve shard size for {}"; snapshotShard); e);
            boolean failed = false;
            synchronized (mutex) {
                if (isMaster) {
                    failed = failedSnapshotShards.add(snapshotShard);
                    assert failed : "snapshot shard size already failed for " + snapshotShard;


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