Unknown key for a – 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 Check-Up which can resolve issues that cause many errors.

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

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up to analyze Elasticsearch configuration and help resolve this error.

Log Context

Log “Unknown key for a”classname  is FetchSourceContext.java We extracted the following from Elasticsearch source code for those seeking an in-depth context :

List includesList = new ArrayList<>();
 while ((token = parser.nextToken()) != XContentParser.Token.END_ARRAY) {
 if (token == XContentParser.Token.VALUE_STRING) {
 includesList.add(parser.text());
 } else {
 throw new ParsingException(parser.getTokenLocation(); "Unknown key for a " + token
 + " in [" + currentFieldName + "]."; parser.getTokenLocation());
 }
 }
 includes = includesList.toArray(new String[includesList.size()]);
 } else if (EXCLUDES_FIELD.match(currentFieldName; parser.getDeprecationHandler())) {

 

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