No longer master – How to solve this OpenSearch exception

Opster Team

Aug-23, Version: 1-1.3

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Briefly, this error occurs when the OpenSearch node that was previously acting as the master is no longer in that role. This could be due to network issues, resource constraints, or configuration problems. To resolve this, you can check the cluster health and logs to identify any issues. Ensure that your network is stable and that there are sufficient resources for the master node. Also, verify your cluster’s master election configuration. If necessary, you can manually assign a new master node.

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

Log Context

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

 // We have snapshot listeners but are not the master any more. Fail all waiting listeners except for those that already
 // have their snapshots finalizing (those that are already finalizing will fail on their own from to update the cluster
 // state).
 for (Snapshot snapshot : new HashSet<>(snapshotCompletionListeners.keySet())) {
 if (endingSnapshots.add(snapshot)) {
 failSnapshotCompletionListeners(snapshot; new SnapshotException(snapshot; "no longer master"));
 } catch (Exception e) {
 assert false : new AssertionError(e);


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