Prefix queries cannot be executed when – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 7.7-7.15

Briefly, this error occurs when ‘prefix’ queries are attempted in Elasticsearch but the ‘allow_expensive_queries’ setting is set to false. This setting is designed to prevent queries that may consume significant resources. To resolve this issue, you can either change your query to a less resource-intensive one, or you can set ‘allow_expensive_queries’ to true. However, be aware that the latter option may impact the performance of your Elasticsearch cluster if the queries are indeed resource-intensive.

This guide will help you check for common problems that cause the log ” [prefix] queries cannot be executed when ‘ ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: index.

Log Context

Log “[prefix] queries cannot be executed when ‘” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 }  @Override
 public Query prefixQuery(String value; MultiTermQuery.RewriteMethod method; boolean caseInsensitive; SearchExecutionContext context) {
 if (context.allowExpensiveQueries() == false) {
 throw new ElasticsearchException("[prefix] queries cannot be executed when '" +
 ALLOW_EXPENSIVE_QUERIES.getKey() + "' is set to false. For optimised prefix queries on text " +
 "fields please enable [index_prefixes].");
 if (caseInsensitive) {


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