Error building fetch sub-phases – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 7.1-8.9

Briefly, this error occurs when Elasticsearch encounters issues while constructing the fetch sub-phases during a search operation. This could be due to a variety of reasons such as incorrect query syntax, insufficient memory, or corrupted indices. To resolve this issue, you can try the following: 1) Check and correct your query syntax. 2) Increase the memory allocation for Elasticsearch if it’s insufficient. 3) Check the health of your indices and repair or rebuild them if necessary. 4) Upgrade Elasticsearch to the latest version as it might be a bug that’s fixed in a newer version.

This guide will help you check for common problems that cause the log ” Error building fetch sub-phases ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: search.

Log Context

Log “Error building fetch sub-phases” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 processors.add(profiler.profile(fsp.getClass().getSimpleName(); ""; processor));
 return processors;
 } catch (Exception e) {
 throw new FetchPhaseExecutionException(target; "Error building fetch sub-phases"; e);
 }  private static HitContext prepareHitContext(
 SearchContext context;


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