No longer master – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 7.7-8.9

Briefly, this error occurs when a node in an Elasticsearch cluster that was previously acting as the master is no longer in that role. This could be due to network issues, resource constraints, or a new master being elected. To resolve this, you can check the cluster health and logs to identify any issues. If it’s a network problem, ensure all nodes are properly connected. If it’s a resource issue, consider adding more resources or nodes. If a new master was elected due to the old one being unresponsive, investigate the cause of the unresponsiveness.

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 Elasticsearch concepts: master, routing, allocation, cluster.

Log Context

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

 if (listeners.isEmpty() == false) {
 threadPool.generic().execute(() -> {
 if (isMaster) {
 ActionListener.onResponse(listeners; null);
 } else {
 ActionListener.onFailure(listeners; new NotMasterException("no longer master"));


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