No master to send allocate dangled request – How to solve this OpenSearch exception

Opster Team

Aug-23, Version: 1-2

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Briefly, this error occurs when OpenSearch cannot find a master node to allocate a dangled index. A dangled index is an index that is not part of the cluster state but has data in the node’s data directory. This can happen due to network issues or if the master node is down. To resolve this issue, ensure that the master node is up and running, check your network connectivity, and verify your cluster health. If the problem persists, consider increasing the number of master nodes or reindexing the dangled indices.

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This guide will help you check for common problems that cause the log ” no master to send allocate dangled request ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: dangled, master, request.

Log Context

Log “no master to send allocate dangled request” class name is We extracted the following from OpenSearch source code for those seeking an in-depth context :

 public void allocateDangled(Collection indices; ActionListener listener) {
 ClusterState clusterState = clusterService.state();
 DiscoveryNode masterNode = clusterState.nodes().getMasterNode();
 if (masterNode == null) {
 listener.onFailure(new MasterNotDiscoveredException("no master to send allocate dangled request"));
 AllocateDangledRequest request = new AllocateDangledRequest(
 indices.toArray(new IndexMetadata[indices.size()])


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