Failed sending request – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-7.14

Briefly, this error occurs when Elasticsearch is unable to send a request due to network issues, firewall restrictions, or the target server being down. To resolve this, you can check the network connection, ensure the target server is running, and verify firewall settings to allow Elasticsearch requests. Additionally, check the Elasticsearch logs for more detailed information about the error.

This guide will help you check for common problems that cause the log ” failed sending request ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: request, plugin.

Log Context

Log “failed sending request” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 }  try {
 sender.sendRequest(connection; action; request; options; handler);
 } catch (Exception e) {
 handler.handleException(new TransportException("failed sending request"; e));
 }  // pkg-private method to allow overriding for tests
 void assertNoAuthentication(String action) {