Failed to prepare warm – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 6.8-8.9

Briefly, this error occurs when Elasticsearch fails to prepare a warm-up query before executing the actual query. This could be due to a variety of reasons such as insufficient resources, incorrect query syntax, or issues with the underlying data. To resolve this issue, you can try increasing system resources, checking the query syntax for errors, or investigating the data for inconsistencies or corruption. Additionally, ensure that the Elasticsearch cluster is properly configured and running smoothly.

This guide will help you check for common problems that cause the log ” failed to prepare/warm ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: index.

Log Context

Log “failed to prepare/warm” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

            if (warmer != null) {
                try {
                } catch (Exception e) {
                    if (isEngineClosed.get() == false) {
                        logger.warn("failed to prepare/warm"; e);


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