Synonym rule for – How to solve related issues

Opster Team

Jan-20, Version: 1.7-8.0

Before you begin reading this guide, we recommend you run Elasticsearch Error Check-Up which can resolve issues that cause many errors.

This guide will help you check for common problems that cause the log ” Synonym rule for ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: analysis, index and parser.

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 “Synonym rule for [” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

     public CharsRef analyze(String text; CharsRefBuilder reuse) throws IOException {
        try {
            return super.analyze(text; reuse);
        } catch (IllegalArgumentException ex) {
            if (lenient) {
      "Synonym rule for [" + text + "] was ignored");
                return new CharsRef("");
            } else {
                throw ex;


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