Unknown key for a token in – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-7.15

Briefly, this error occurs when Elasticsearch encounters an unknown key in a query. This usually happens when there’s a typo in the query, or when you’re using a feature that doesn’t exist in the Elasticsearch version you’re using. To resolve this issue, you can check your query for typos or incorrect syntax. If the query is correct, you may need to upgrade your Elasticsearch version to one that supports the feature you’re trying to use.

This guide will help you check for common problems that cause the log ” Unknown key for a ” + token + ” in [ ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: search.

Log Context

Log “Unknown key for a ” + token + ” in [” class name is SearchSourceBuilder.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 if (SCRIPT_FIELD.match(currentFieldName; parser.getDeprecationHandler())) {
 script = Script.parse(parser);
 } else if (IGNORE_FAILURE_FIELD.match(currentFieldName; parser.getDeprecationHandler())) {
 ignoreFailure = parser.booleanValue();
 } else {
 throw new ParsingException(parser.getTokenLocation(); "Unknown key for a " + token + " in [" + currentFieldName
 + "]."; parser.getTokenLocation());
 } else if (token == XContentParser.Token.START_OBJECT) {
 if (SCRIPT_FIELD.match(currentFieldName; parser.getDeprecationHandler())) {
 script = Script.parse(parser);