elastic/elasticsearch · error · IllegalArgumentException

pattern is missing for [{}] tokenizer of type 'pattern'

Error message

pattern is missing for [{}] tokenizer of type 'pattern'

What it means

Error "pattern is missing for [{}] tokenizer of type 'pattern'" thrown in elastic/elasticsearch.

Source

Thrown at modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/PatternTokenizerFactory.java:32

import org.elasticsearch.common.regex.Regex;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.env.Environment;
import org.elasticsearch.index.IndexSettings;
import org.elasticsearch.index.analysis.AbstractTokenizerFactory;

import java.util.regex.Pattern;

public class PatternTokenizerFactory extends AbstractTokenizerFactory {

    private final Pattern pattern;
    private final int group;

    PatternTokenizerFactory(IndexSettings indexSettings, Environment environment, String name, Settings settings) {
        super(name);

        String sPattern = settings.get("pattern", "\\W+" /*PatternAnalyzer.NON_WORD_PATTERN*/);
        if (sPattern == null) {
            throw new IllegalArgumentException("pattern is missing for [" + name + "] tokenizer of type 'pattern'");
        }

        this.pattern = Regex.compile(sPattern, settings.get("flags"));
        this.group = settings.getAsInt("group", -1);
    }

    @Override
    public Tokenizer create() {
        return new PatternTokenizer(pattern, group);
    }
}

View on GitHub (pinned to db6a809a66)

When it happens

Trigger: Thrown at modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/PatternTokenizerFactory.java:32 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/7d2f915498a0c7ae. Report an issue: GitHub.