elastic/elasticsearch · error · IllegalArgumentException

required setting 'patterns' is missing for token filter [{}]

Error message

required setting 'patterns' is missing for token filter [{}]

What it means

Error "required setting 'patterns' is missing for token filter [{}]" thrown in elastic/elasticsearch.

Source

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

import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.env.Environment;
import org.elasticsearch.index.IndexSettings;
import org.elasticsearch.index.analysis.AbstractTokenFilterFactory;

import java.util.List;
import java.util.regex.Pattern;

public class PatternCaptureGroupTokenFilterFactory extends AbstractTokenFilterFactory {
    private final Pattern[] patterns;
    private final boolean preserveOriginal;
    private static final String PATTERNS_KEY = "patterns";
    private static final String PRESERVE_ORIG_KEY = "preserve_original";

    PatternCaptureGroupTokenFilterFactory(IndexSettings indexSettings, Environment environment, String name, Settings settings) {
        super(name);
        List<String> regexes = settings.getAsList(PATTERNS_KEY, null, false);
        if (regexes == null) {
            throw new IllegalArgumentException("required setting '" + PATTERNS_KEY + "' is missing for token filter [" + name + "]");
        }
        patterns = new Pattern[regexes.size()];
        for (int i = 0; i < regexes.size(); i++) {
            patterns[i] = Pattern.compile(regexes.get(i));
        }

        preserveOriginal = settings.getAsBoolean(PRESERVE_ORIG_KEY, true);
    }

    @Override
    public TokenFilter create(TokenStream tokenStream) {
        return new PatternCaptureGroupTokenFilter(tokenStream, preserveOriginal, patterns);
    }
}

View on GitHub (pinned to db6a809a66)

When it happens

Trigger: Thrown at modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/PatternCaptureGroupTokenFilterFactory.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/f69a27165c443c4e. Report an issue: GitHub.