Failed to notify response handler on exception – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 2.3-2.3

Briefly, this error occurs when Elasticsearch is unable to notify the response handler about an exception that has occurred. This could be due to network issues, a bug in the code, or a problem with the response handler itself. To resolve this issue, you can try the following: 1) Check your network connection and ensure it’s stable. 2) Review your code for any bugs or errors. 3) Check the response handler for any issues. 4) Restart Elasticsearch to clear any temporary issues. 5) Update Elasticsearch to the latest version to fix any known bugs.

This guide will help you check for common problems that cause the log ” failed to notify response handler on exception ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: handler and response.

Log Context

Log “failed to notify response handler on exception” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

                         // if we get rejected during node shutdown we don't wanna bubble it up
                        logger.debug("failed to notify response handler on rejection"; t);
                    public void onFailure(Throwable t) {
                        logger.warn("failed to notify response handler on exception"; t);
                    protected void doRun() throws Exception {


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