Failure to send – How to solve this Elasticsearch error

Opster Team

July-20, Version: 1.7-8.0

Before you begin reading this guide, we recommend you try running the Elasticsearch Check-Up which can resolve issues that cause many errors.

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

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up to analyze Elasticsearch configuration and help resolve this error.

Log Context

Log “failure to send”classname  is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

() -> handler.handleLocalException(new ConnectTransportException(node; "handshake_timeout[" + timeout + "]"));
 success = true;
 } catch (Exception e) {
 handler.handleLocalException(new ConnectTransportException(node; "failure to send " + HANDSHAKE_ACTION_NAME; e));
 } finally {
 if (success == false) {
 TransportResponseHandler removed = pendingHandshakes.remove(requestId);
 assert removed == null : "Handshake should not be pending if exception was thrown";


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