elastic/elasticsearch · error · IllegalArgumentException

Analyzer [{}] of type pattern must have a `pattern` set

Error message

Analyzer [{}] of type pattern must have a `pattern` set

What it means

Error "Analyzer [{}] of type pattern must have a `pattern` set" thrown in elastic/elasticsearch.

Source

Thrown at modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/PatternAnalyzerProvider.java:36

import org.elasticsearch.index.analysis.AbstractIndexAnalyzerProvider;
import org.elasticsearch.index.analysis.Analysis;

import java.util.regex.Pattern;

public class PatternAnalyzerProvider extends AbstractIndexAnalyzerProvider<Analyzer> {

    private final PatternAnalyzer analyzer;

    PatternAnalyzerProvider(IndexSettings indexSettings, Environment env, String name, Settings settings) {
        super(name);

        final CharArraySet defaultStopwords = CharArraySet.EMPTY_SET;
        boolean lowercase = settings.getAsBoolean("lowercase", true);
        CharArraySet stopWords = Analysis.parseStopWords(env, settings, defaultStopwords);

        String sPattern = settings.get("pattern", "\\W+" /*PatternAnalyzer.NON_WORD_PATTERN*/);
        if (sPattern == null) {
            throw new IllegalArgumentException("Analyzer [" + name + "] of type pattern must have a `pattern` set");
        }
        Pattern pattern = Regex.compile(sPattern, settings.get("flags"));

        analyzer = new PatternAnalyzer(pattern, lowercase, stopWords);
    }

    @Override
    public PatternAnalyzer get() {
        return analyzer;
    }
}

View on GitHub (pinned to db6a809a66)

When it happens

Trigger: Thrown at modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/PatternAnalyzerProvider.java:36 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/e4fe763f9135e547. Report an issue: GitHub.