Can t open connection to a null node – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.9

Briefly, this error occurs when Elasticsearch tries to establish a connection with a node that doesn’t exist or is not properly defined, hence referred to as a ‘null’ node. This could be due to incorrect configuration or network issues. To resolve this, ensure that the node is correctly defined in your configuration, check your network settings, and verify that the node is up and running. If the problem persists, consider restarting Elasticsearch or the specific node causing the issue.

This guide will help you check for common problems that cause the log ” can’t open connection to a null node ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: node.

Log Context

Log “can’t open connection to a null node” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 public void openConnection(DiscoveryNode node; ConnectionProfile profile; ActionListener listener) {  Objects.requireNonNull(profile; "connection profile cannot be null");
 if (node == null) {
 throw new ConnectTransportException(null; "can't open connection to a null node");
 ConnectionProfile finalProfile = maybeOverrideConnectionProfile(profile);
 if (closeLock.readLock().tryLock() == false) {
 assert false : "should not get here ever because close-write-lock should only be held on shutdown";


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