Could not read search request unexpected string field – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-7.15

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Briefly, this error occurs when Elasticsearch receives a search request with an unexpected string field. This usually happens when there’s a mismatch between the field type in the request and the field type defined in the Elasticsearch index. To resolve this issue, you can either modify the search request to match the field type in the index or update the index mapping to accommodate the field type in the request. Also, ensure that the field exists in the index and the correct syntax is used in the search request.

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This guide will help you check for common problems that cause the log ” could not read search request. unexpected string field [ ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin, request, search.

Log Context

Log “could not read search request. unexpected string field [” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 } else if (SEARCH_TYPE_FIELD.match(currentFieldName; parser.getDeprecationHandler())) {
 searchType = SearchType.fromString(parser.text().toLowerCase(Locale.ROOT));
 } else if (REST_TOTAL_HITS_AS_INT_FIELD.match(currentFieldName; parser.getDeprecationHandler())) {
 totalHitsAsInt = parser.booleanValue();
 } else {
 throw new ElasticsearchParseException("could not read search request. unexpected string field [" +
 currentFieldName + "]");
 } else if (token == XContentParser.Token.VALUE_BOOLEAN) {
 if (REST_TOTAL_HITS_AS_INT_FIELD.match(currentFieldName; parser.getDeprecationHandler())) {
 totalHitsAsInt = parser.booleanValue();


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