No longer master source source – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.2

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Briefly, this error occurs when the Elasticsearch 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 the master node is properly configured and has sufficient resources. If network issues are suspected, verify the connectivity between nodes. Also, consider increasing the ‘discovery.zen.minimum_master_nodes’ setting to prevent split-brain scenarios.

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This guide will help you check for common problems that cause the log ” no longer master. source: [” + source + “] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: admin, master, cluster.

Log Context

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

 public void onNoLongerMaster() {
 logger.trace("stopped being master while waiting for events with priority [{}]. retrying."; request.waitForEvents());
 // TransportMasterNodeAction implements the retry logic; which is triggered by passing a NotMasterException
 listener.onFailure(new NotMasterException("no longer master. source: [" + source + "]"));
 }  @Override
 public void onFailure(Exception e) {
 if (e instanceof ProcessClusterEventTimeoutException) {


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