Failed to build aggregation aggregator name – How to solve this OpenSearch exception

Opster Team

Aug-23, Version: 1-2.9

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Briefly, this error occurs when OpenSearch fails to construct an aggregation due to incorrect or missing parameters in the aggregation query. This could be due to a wrong field name, incorrect data type, or a missing required parameter. To resolve this issue, you should first verify the field names and data types in your query. Ensure that the field you’re trying to aggregate exists in your index and is of the correct type. Also, check your aggregation syntax to ensure all required parameters are included and correctly formatted.

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This guide will help you check for common problems that cause the log ” Failed to build aggregation [” + + “] ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: aggregations, search.

Log Context

Log “Failed to build aggregation [” + + “]” class name is We extracted the following from OpenSearch source code for those seeking an in-depth context :

 for (Aggregator aggregator : aggregators) {
 try {
 } catch (IOException e) {
 throw new AggregationExecutionException("Failed to build aggregation [" + + "]"; e);
 }  // PipelineTreeSource is serialized to the coordinators on older OpenSearch versions for bwc but is deprecated in latest release
 // To handle that we need to add it in the InternalAggregations object sent in QuerySearchResult.


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