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

Opster Team

August-23, Version: 7.2-8.9

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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.

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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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