Rescore Phase Failed – How to solve this OpenSearch exception

Opster Team

Aug-23, Version: 1-2.9

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Briefly, this error occurs when OpenSearch encounters an issue during the rescore phase of a query. The rescore phase is used to improve the relevance of the search results. The error could be due to a misconfiguration in the rescore query or a lack of system resources. To resolve this, you can try to simplify the rescore query or increase the system resources. Additionally, ensure that the rescore window size is not set too high as it can consume a lot of memory and cause the rescore phase to fail.

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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 OpenSearch concepts: search.

Log Context

Log “Rescore Phase Failed” class name is We extracted the following from OpenSearch 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 OpenSearchException("Rescore Phase Failed"; e);
 }  /**
 * Returns true if the provided docs are sorted by score.


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