elastic/elasticsearch · error · IllegalArgumentException

Token filter [{}] cannot be used to parse synonyms

Error message

Token filter [{}] cannot be used to parse synonyms

What it means

Error "Token filter [{}] cannot be used to parse synonyms" thrown in elastic/elasticsearch.

Source

Thrown at modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/NGramTokenFilterFactory.java:53

                    + maxAllowedNgramDiff
                    + "] but was ["
                    + ngramDiff
                    + "]. This limit can be set by changing the ["
                    + IndexSettings.MAX_NGRAM_DIFF_SETTING.getKey()
                    + "] index level setting."
            );
        }
        preserveOriginal = settings.getAsBoolean(PRESERVE_ORIG_KEY, false);
    }

    @Override
    public TokenStream create(TokenStream tokenStream) {
        return new NGramTokenFilter(tokenStream, minGram, maxGram, preserveOriginal);
    }

    @Override
    public TokenFilterFactory getSynonymFilter() {
        throw new IllegalArgumentException("Token filter [" + name() + "] cannot be used to parse synonyms");
    }
}

View on GitHub (pinned to db6a809a66)

When it happens

Trigger: Thrown at modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/NGramTokenFilterFactory.java:53 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of elastic/elasticsearch@db6a809a66 (2026-08-12). Data as JSON: /api/errors/44328339d253860b. Report an issue: GitHub.