Rescore Phase Failed – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.9

Briefly, this error occurs when Elasticsearch encounters an issue during the rescore phase of a query. The rescore phase is used to improve the relevance of the top documents returned by the query. This error could be due to a problem with the rescore query itself or a system resource issue. To resolve this, you can check the rescore query for errors, ensure that your system has sufficient resources, or try reducing the window size of the rescore query to lessen the load on the system.

This guide will help you check for common problems that cause the log ” Rescore Phase Failed ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: search.

Log Context

Log “Rescore Phase Failed” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 assert context.sort() == null && topDocsSortedByScore(topDocs) : "topdocs should be sorted after rescore";
 .topDocs(new TopDocsAndMaxScore(topDocs; topDocs.scoreDocs[0].score); context.queryResult().sortValueFormats());
 } catch (IOException e) {
 throw new ElasticsearchException("Rescore Phase Failed"; e);
 }  /**
 * Returns true if the provided docs are sorted by score.


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