Unknown field – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.9

Briefly, this error occurs when Elasticsearch encounters a field in the query that it doesn’t recognize or isn’t mapped in the index. This could be due to a typo in the field name or the field not being defined in the index mapping. To resolve this issue, you can check the field name for typos, ensure the field is correctly defined in the index mapping, or use the “_source” field to return the original document if the field is not needed for querying or aggregations.

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

Log Context

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

 MultiValueMode mode
 ) throws IOException {
 // the field must exist; else we cannot read the value for the doc later
 MappedFieldType fieldType = context.getFieldType(fieldName);
 if (fieldType == null) {
 throw new ParsingException(parser.getTokenLocation(); "unknown field [{}]"; fieldName);
 }  // dates and time and geo need special handling
 // TODO these ain't gonna work with runtime fields


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