Failed to parse rules expression. field requires an array – How to solve this Elasticsearch error

Opster Team

July-20, Version: 1.7-8.0

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This guide will help you check for common problems that cause the log ” failed to parse rules expression. field requires an array ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: parser, rest-high-level and client.

Log Context

Log “failed to parse rules expression. field [{}] requires an array”classname  is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

while (parser.nextToken() != XContentParser.Token.END_ARRAY) {
 return list;
 } else {
 throw new ElasticsearchParseException("failed to parse rules expression. field [{}] requires an array"; field);
 private Object parseFieldValue(XContentParser parser) throws IOException {
 switch (parser.currentToken()) {


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