Node leader failed health checks – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 7.9-7.15

Briefly, this error occurs when the Elasticsearch node, referred to as the “leader”, fails to pass the health checks. This could be due to issues like insufficient memory, network connectivity problems, or disk space issues. To resolve this, you can check the node’s logs for specific errors, ensure there’s enough disk space, and verify network connectivity. Also, check the JVM heap size to ensure it’s not too low or high. Restarting the node or the entire cluster can also help. If the problem persists, consider reconfiguring your cluster or upgrading Elasticsearch.

This guide will help you check for common problems that cause the log ” node [” + leader + “] failed health checks ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: cluster, node, checks.

Log Context

Log “node [” + leader + “] failed health checks” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 leaderFailed(new ConnectTransportException(leader; "disconnected during check"; exp));
 } else if (exp.getCause() instanceof NodeHealthCheckFailureException) {
 logger.debug(new ParameterizedMessage(
 "leader [{}] health check failed"; leader); exp);
 leaderFailed(new NodeHealthCheckFailureException("node [" + leader + "] failed health checks"; exp));
 long failureCount = failureCountSinceLastSuccess.incrementAndGet();
 if (failureCount >= leaderCheckRetryCount) {
 logger.debug(new ParameterizedMessage(