Dropping a warning header as their total count reached the maximum allowed of – How to solve this OpenSearch error

Opster Team

Aug-23, Version: 1-1.1

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Briefly, this error occurs when the total count of warning headers in OpenSearch reaches the maximum limit. This could be due to a large number of warnings generated by queries or operations. To resolve this, you can review and optimize your queries to reduce the number of warnings. Additionally, you can increase the maximum limit of warning headers, but this should be done cautiously as it may impact the performance. Lastly, ensure your application handles and logs warnings appropriately to avoid unnecessary accumulation.

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This guide will help you check for common problems that cause the log ” Dropping a warning header; as their total count reached the maximum allowed of [ ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: .

Log Context

Log “Dropping a warning header; as their total count reached the maximum allowed of [” classname is ThreadContext.java.
We extracted the following from OpenSearch source code for those seeking an in-depth context :

            //check if we can add another warning header - if max count within limits
            if ((key.equals("Warning")) && (maxWarningHeaderCount != -1)) { //if count is NOT unbounded; check its limits
                final int warningHeaderCount = newResponseHeaders.containsKey("Warning") ? newResponseHeaders.get("Warning").size() : 0;
                if (warningHeaderCount > maxWarningHeaderCount) {
                    logger.warn("Dropping a warning header; as their total count reached the maximum allowed of ["
                            + maxWarningHeaderCount + "] set in ["
                            + HttpTransportSettings.SETTING_HTTP_MAX_WARNING_HEADER_COUNT.getKey() + "]!");
                    return this;


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