Opster Team
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.
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.
Take a self-guided product tour to see for yourself (no registration required).This guide will help you check for common problems that cause the log ” key settings must be an object ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: admin and indices.

Log Context
Log “key [settings] must be an object”classname is CreateIndexRequest.java We extracted the following from Elasticsearch source code for those seeking an in-depth context :
public CreateIndexRequest source(Mapsource; DeprecationHandler deprecationHandler) { for (Map.Entry entry : source.entrySet()) { String name = entry.getKey(); if (SETTINGS.match(name; deprecationHandler)) { if (entry.getValue() instanceof Map == false) { throw new ElasticsearchParseException("key [settings] must be an object"); } settings((Map ) entry.getValue()); } else if (MAPPINGS.match(name; deprecationHandler)) { Map mappings = (Map ) entry.getValue(); for (Map.Entry entry1 : mappings.entrySet()) {
Find & fix Elasticsearch problems
Opster AutoOps diagnoses & fixes issues in Elasticsearch based on analyzing hundreds of metrics.
Fix Your Cluster IssuesConnect in under 2 minutes
Billy McCarthy
Senior SysAdmin at Backblaze