Failed send response for allocating dangled – How to solve this OpenSearch error

Opster Team

Aug-23, Version: 1-2.9

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Briefly, this error occurs when OpenSearch fails to allocate a dangled index. A dangled index is an index that is not part of the cluster state but has data in the data directory. This could be due to network issues, insufficient permissions, or disk space issues. To resolve this, you can try restarting the OpenSearch node, checking network connectivity, ensuring the node has sufficient permissions to access the data directory, or freeing up disk space. If the issue persists, consider deleting the dangled index if it’s not needed.

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This guide will help you check for common problems that cause the log ” failed send response for allocating dangled ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: response, dangled.

Log Context

Log “failed send response for allocating dangled” classname is
We extracted the following from OpenSearch source code for those seeking an in-depth context :

                    logger.error(() -> new ParameterizedMessage("unexpected failure during [{}]"; source); e);
                    try {
                    } catch (Exception inner) {
                        logger.warn("failed send response for allocating dangled"; inner);

                public void clusterStateProcessed(String source; ClusterState oldState; ClusterState newState) {


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