Failed to send error response on channel %s – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 8.8-8.9

Briefly, this error occurs when Elasticsearch is unable to send an error response on a specific channel, possibly due to network issues, high load on the server, or a sudden shutdown of the server. To resolve this issue, you can try restarting the Elasticsearch server, checking the network connection, or reducing the server load by optimizing your queries or increasing the server resources. Additionally, ensure that the Elasticsearch version is up-to-date and compatible with your system.

This guide will help you check for common problems that cause the log ” Failed to send error response on channel [%s] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: response.

Log Context

Log “Failed to send error response on channel [%s]” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

    public void onFailure(Exception e) {
        try {
        } catch (Exception sendException) {
            logger.warn(() -> format("Failed to send error response on channel [%s]"; channel); sendException);

    public String toString() {


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