Failed to parse object Expected START OBJECT but was – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 7.2-8.9

Briefly, this error occurs when Elasticsearch expects a JSON object to start (denoted by ‘{‘) but encounters a different type of data. This usually happens when the JSON data structure is incorrect or malformed. To resolve this issue, you can: 1) Check the JSON input for any syntax errors or misplaced brackets. 2) Validate your JSON data using a JSON validator tool. 3) Ensure that the JSON data structure matches the expected structure in your Elasticsearch query or operation.

This guide will help you check for common problems that cause the log ” Failed to parse object: Expected START_OBJECT but was: ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin.

Log Context

Log “Failed to parse object: Expected START_OBJECT but was:” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 // be parsing friendly; whether the token needs to be advanced or not (similar to what ObjectParser does)
 XContentParser.Token token;
 if (parser.currentToken() != XContentParser.Token.START_OBJECT) {
 token = parser.nextToken();
 if (token != XContentParser.Token.START_OBJECT) {
 throw new ParsingException(parser.getTokenLocation(); "Failed to parse object: Expected START_OBJECT but was: " + token);
 }  while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {


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