Expecting Json Field name token after the Start Object token – How to solve related issues

Opster Team

Jan-20, Version: 1.7-8.0

Before you begin reading this guide, we recommend you run Elasticsearch Error Check-Up which analyzes 2 JSON files to detect many errors.

Briefly, this error message indicates that Elasticsearch was expecting to receive a JSON field name after an opening brace (‘{‘), but instead received another character. This error is usually caused by a malformed request or incorrectly formatted JSON payload. To resolve the issue, you can try examining the request payload and ensuring that it follows the correct JSON format and syntax.

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 ” Expecting Json Field name token after the Start Object token ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: parser and plugin.

Log Context

Log “Expecting Json Field name token after the Start Object token” classname is AutodetectResultsParser.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

            if (token == XContentParser.Token.END_ARRAY) {
                return false;
            } else if (token != XContentParser.Token.START_OBJECT) {
                logger.error("Expecting Json Field name token after the Start Object token");
                throw new ElasticsearchParseException("unexpected token [" + token + "]");
            return true;


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