Unknown key for index template – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.9

Briefly, this error occurs when Elasticsearch encounters an unrecognized key in the index template. This could be due to a typo, incorrect syntax, or usage of a key that is not supported in the current version of Elasticsearch. To resolve this issue, you should first verify the keys used in your index template against the Elasticsearch documentation for your version. Ensure that all keys are spelled correctly and are in the correct format. If the error persists, consider upgrading your Elasticsearch version to one that supports the key in question.

This guide will help you check for common problems that cause the log ” unknown key [{}] for index template ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: index, metadata, template, cluster.

Log Context

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

 } else if ("aliases".equals(currentFieldName)) {
 while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
 } else {
 throw new ElasticsearchParseException("unknown key [{}] for index template"; currentFieldName);
 } else if (token == XContentParser.Token.START_ARRAY) {
 if ("mappings".equals(currentFieldName)) {
 while ((token = parser.nextToken()) != XContentParser.Token.END_ARRAY) {
 Map mapping = parser.mapOrdered();


How helpful was this guide?

We are sorry that this post was not useful for you!

Let us improve this post!

Tell us how we can improve this post?