_key must be the last element in the path – How to solve this Elasticsearch error

Opster Team

July-20, Version: 1.7-8.0

Before you begin reading this guide, we recommend you try running the Elasticsearch Check-Up which can resolve issues that cause many errors.

This guide will help you check for common problems that cause the log ” _key must be the last element in the path ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: search and aggregations.

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up to analyze Elasticsearch configuration and help resolve this error.

Log Context

Log “_key must be the last element in the path”classname  is InternalMultiBucketAggregation.java We extracted the following from Elasticsearch source code for those seeking an in-depth context :

throw new InvalidAggregationPathException("_count must be the last element in the path");
 }
 return getDocCount();
 } else if (aggName.equals("_key")) {
 if (path.size() > 1) {
 throw new InvalidAggregationPathException("_key must be the last element in the path");
 }
 return getKey();
 }
 InternalAggregation aggregation = aggregations.get(aggName);
 if (aggregation == null) {

 

Try AutoOps to detect and fix issues in your cluster:

Analyze Your Cluster

Skip to content