Log Failed to prepare/warm – How To Solve Related Issues

Log Failed to prepare/warm – How To Solve Related Issues

Opster Team

Jan-20, Version: 1.7-8.0


Before you begin reading this guide, we recommend you try running the Elasticsearch Error Check-Up  which can resolve issues causing many log errors (free and no installation required)


This guide will help you check for common problems that cause the log “Failed to prepare/warm” to appear. It’s important to understand the issues related to the log, so to get started, read the general overview on common issues and tips related to the Elasticsearch concepts: index.

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up which analyses ES to discover the cause of many errors and provides suitable actionable recommendations. 

Log Context

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

                     assert searcher.getIndexReader() instanceof ElasticsearchDirectoryReader :
                        "this class needs an ElasticsearchDirectoryReader but got: " + searcher.getIndexReader().getClass();
                    warmer.warm(new Searcher("top_reader_warming"; searcher; () -> {}));
                } catch (Exception e) {
                    if (isEngineClosed.get() == false) {
                        logger.warn("failed to prepare/warm"; e);
            return searcher;

Related issues to this log

We have gathered selected Q&A from the community and issues from Github, that can help fix related issues please review the following for further information :

1 Elasticsearch unable to create native thread -views 0.36 K ,score –

Warning Failed To Prepare Warm Afte  

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