Failed to parse rules expression expected an object but found instead – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.9

Briefly, this error occurs when Elasticsearch expects a set of rules in a specific format (an object), but it encounters an empty object [{}]. This could be due to incorrect syntax or a missing value. To resolve this issue, you should review the rules expression for any syntax errors or missing values. Ensure that the rules are correctly formatted as an object and that all required fields are included. If the error persists, consider validating your rules expression with a JSON validator to identify any hidden issues.

This guide will help you check for common problems that cause the log ” failed to parse rules expression. expected an object but found [{}] instead ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin.

Log Context

Log “failed to parse rules expression. expected an object but found [{}] instead” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 }  private void checkStartObject(XContentParser parser) throws IOException {
 final XContentParser.Token token = parser.nextToken();
 if (token != XContentParser.Token.START_OBJECT) {
 throw new ElasticsearchParseException("failed to parse rules expression. expected an object but found [{}] instead"; token);
 }  private String readFieldName(String objectName; XContentParser parser) throws IOException {
 if (parser.nextToken() != XContentParser.Token.FIELD_NAME) {


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