No known master nodes – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-7.17

Briefly, this error occurs when Elasticsearch cannot find any master-eligible nodes in the cluster. This could be due to network issues, configuration errors, or all master-eligible nodes being down. To resolve this, ensure that your network is functioning properly and that your nodes are correctly configured to discover each other. Also, check the health of your master-eligible nodes and restart them if necessary. If the issue persists, consider increasing the number of master-eligible nodes in your cluster.

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

Log Context

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

 } else {
 // Delegates DeleteJob to elected master node; so it becomes the coordinating node.
 // Non-master nodes may have a stale cluster state that shows jobs which are cancelled
 // on the master; which makes testing difficult.
 if (nodes.getMasterNode() == null) {
 listener.onFailure(new MasterNotDiscoveredException("no known master nodes"));
 } else {


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