Failed to parse object: Expected START_OBJECT but was: – 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 Error Check-Up which analyzes 2 JSON files to detect many configuration errors.

Briefly, this error message typically indicates that Elasticsearch received an invalid request from a client that could not be parsed correctly. This could be caused by incorrect syntax or an incompatible API version, among other things. To resolve this issue, double-check the syntax of the request and ensure that the correct API version is being used.

To easily locate the root cause and resolve this issue try AutoOps for Elasticsearch & OpenSearch. It diagnoses problems by analyzing hundreds of metrics collected by a lightweight agent and offers guidance for resolving them.

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: rest-high-level and client.

Log Context

Log “Failed to parse object: Expected START_OBJECT but was:”classname  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) {
 ensureExpectedToken(XContentParser.Token.FIELD_NAME; token; parser::getTokenLocation);


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