Master left reason – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 6.8-6.8

Briefly, this error occurs when the master node in an Elasticsearch cluster is no longer available or has been disconnected. This could be due to network issues, resource constraints, or the master node crashing. To resolve this issue, you can check the health of your cluster and ensure all nodes are properly connected. If the master node has crashed, restart it. If resource constraints are the issue, consider adding more resources or nodes to your cluster. Also, ensure your network is stable and reliable to prevent disconnections.

This guide will help you check for common problems that cause the log ” Master_left [{}]; reason [{}] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: discovery.

Log Context

Log “Master_left [{}]; reason [{}]” classname is ZenDiscovery.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

         if (localNodeMaster()) {
            // we might get this on both a master telling us shutting down; and then the disconnect failure
            return;
        }

        logger.info(() -> new ParameterizedMessage("master_left [{}]; reason [{}]"; masterNode; reason); cause);

        synchronized (stateMutex) {
            if (localNodeMaster() == false && masterNode.equals(committedState.get().nodes().getMasterNode())) {
                // flush any pending cluster states from old master; so it will not be set as master again
                pendingStatesQueue.failAllStatesAndClear(new ElasticsearchException("master left [{}]"; reason));




 

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