Synonym rule for text was ignored – How to solve this OpenSearch error

Opster Team

Aug-23, Version: 1-2.9

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Briefly, this error occurs when OpenSearch encounters a synonym rule that it cannot process, usually due to incorrect formatting or syntax. The text within the brackets is the problematic synonym rule. To resolve this issue, you should first verify the syntax of your synonym rules. Ensure that they are correctly formatted and do not contain any illegal characters. If the syntax is correct, check if the rule is applicable to the field data type. Lastly, ensure that the synonym rule does not create a circular reference, as this can also cause the rule to be ignored.

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This guide will help you check for common problems that cause the log ” Synonym rule for [” + text + “] was ignored ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: analysis.

Log Context

Log “Synonym rule for [” + text + “] was ignored” classname is
We extracted the following from OpenSearch 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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