Could not identify key in agg k – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.9

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Briefly, this error occurs when Elasticsearch is unable to identify a key in an aggregation. This could be due to a typo in the key name, a missing key, or a mismatch between the key type and the expected type. To resolve this issue, you can check the spelling and case of your keys, ensure all necessary keys are included, and verify that the key types match the expected types. If the problem persists, consider simplifying your aggregation to isolate the problematic key.

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This guide will help you check for common problems that cause the log ” Could not identify key in agg [” + k + “] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin.

Log Context

Log “Could not identify key in agg [” + k + “]” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 idGenerator.add((Double) v);
 } else {
 throw new RuntimeException("Encountered value of type [" + v.getClass() + "]; which was unable to be processed.");
 } else {
 throw new ElasticsearchException("Could not identify key in agg [" + k + "]");
 }  private static void processMetrics(List metrics; Map doc) {


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