Unknown key in the template – 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 occurs when a template in Elasticsearch contains an unknown key. This can be due to a typo in the template or an outdated template. To resolve this issue, you can check the syntax of the template and ensure that all keys are correct.

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 ” unknown key in the template ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: admin, indices and template.

Log Context

Log “unknown key [{}] in the template”classname  is PutIndexTemplateRequest.java We extracted the following from Elasticsearch source code for those seeking an in-depth context :

mapping((Map) entry1.getValue());
 } else if (name.equals("aliases")) {
 aliases((Map) entry.getValue());
 } else {
 throw new ElasticsearchParseException("unknown key [{}] in the template "; name);
 return this;


See how you can use AutoOps to resolve issues

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