Failed to send bad request response – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 6.8-8.9

Briefly, this error occurs when Elasticsearch is unable to send a response due to a malformed or invalid request. This could be due to incorrect syntax, invalid data, or a request that exceeds the server’s capacity. To resolve this issue, you can: 1) Check the syntax of your request to ensure it’s correct. 2) Validate the data you’re sending to ensure it’s in the correct format. 3) Reduce the size of your request if it’s too large. 4) Check the server logs for more detailed error information.

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

Log Context

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

        } catch (final IOException e) {
            if (cause != null) {
            logger.warn("failed to send bad request response"; e);
            channel.sendResponse(new RestResponse(INTERNAL_SERVER_ERROR; RestResponse.TEXT_CONTENT_TYPE; BytesArray.EMPTY));

    private void dispatchRequest(RestRequest request; RestChannel channel; RestHandler handler; ThreadContext threadContext)


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