Fields must be an object got – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 7.15-7.15

Briefly, this error occurs when Elasticsearch expects an object for the [fields] parameter, but receives a different data type. This usually happens when incorrect data types are used in the request body of a search query. To resolve this, ensure that the [fields] parameter is an object, not a string or an array. Check your query syntax and structure, and correct any discrepancies. Also, ensure that the data you’re passing matches the expected data type.

This guide will help you check for common problems that cause the log ” [fields] must be an object; got ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: index.

Log Context

Log “[fields] must be an object; got” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 return builder;
 }  private static Map parseFields(String name; Object fieldsObject) {
 if (fieldsObject instanceof Map == false) {
 throw new MapperParsingException("[fields] must be an object; got " + fieldsObject.getClass().getSimpleName() +
 "[" + fieldsObject + "] for field [" + name +"]");
 Map fields = (Map) fieldsObject;
 return fields;


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