languagetool-org/languagetool · error · PatternRuleNotFoundException

PatternRuleNotFoundException(ruleId, language)

Error message

PatternRuleNotFoundException(ruleId, language)

What it means

getRuleById looks up pattern rules by their ID for the given language and throws PatternRuleNotFoundException when no rule with that ID resolves. It means the requested rule ID does not exist (or is not a PatternRule) in the loaded rule set for that language.

Source

Thrown at languagetool-wikipedia/src/main/java/org/languagetool/dev/index/Searcher.java:263

      indexSearcher.search(query, collector);
    } catch (TimeLimitingCollector.TimeExceededException e) {
      timeLimitActivated = true;
    }
    return new PossiblyLimitedTopDocs(topCollector.topDocs(), timeLimitActivated);
  }

  List<PatternRule> getRuleById(String ruleId, Language language) throws IOException {
    List<PatternRule> rules = new ArrayList<>();
    JLanguageTool lt = new JLanguageTool(language);
    for (Rule rule : lt.getAllRules()) {
      if (rule.getId().equals(ruleId) && rule instanceof PatternRule) {
        rules.add((PatternRule) rule);
      }
    }
    if (rules.size() > 0) {
      return rules;
    } else {
      throw new PatternRuleNotFoundException(ruleId, language);
    }
  }

  private MatchingSentencesResult findMatchingSentences(IndexSearcher indexSearcher, TopDocs topDocs, JLanguageTool languageTool) throws IOException {
    List<MatchingSentence> matchingSentences = new ArrayList<>();
    int i = 0;
    int docsChecked = 0;
    for (ScoreDoc match : topDocs.scoreDocs) {
      i++;
      if (i < skipHits) {
        // needed for paging
        continue;
      }
      Document doc = indexSearcher.doc(match.doc);
      String sentence = doc.get(fieldName);
      if (sentence == null) {
        throw new RuntimeException("No field '" + fieldName + "' found in doc " + match.doc);
      }

View on GitHub (pinned to 2e990059ce)

Solutions

1. Check the rule ID spelling against the language's rule definitions
2. Verify the language passed matches the language the rule belongs to
3. List available rules for the language and pick a valid ID
4. If the rule was renamed in a LanguageTool upgrade, update the ID

Example fix

// before
java ... --rule Id_Wrong --lang en
// after
java ... --rule EN_A_VS_AN --lang en

List<Rule> all = languageTool.getRelevantRules(...); // or JLanguageTool rule listing
boolean exists = ruleIdsFor(language).contains(ruleId);
if (!exists) { System.err.println("Unknown rule " + ruleId + " for " + language); System.exit(2); }

try {
  rules = searcher.getRuleById(ruleId, language);
} catch (PatternRuleNotFoundException e) {
  System.err.println("Rule not found: " + e.getMessage());
}

When it happens

Trigger: Passing a ruleId on the command line (main) that no PatternRule matches for the specified language — typo, wrong language, or a rule that exists only in a newer/older LanguageTool version.

Common situations: CLI invocation of the Wikipedia indexing/search tooling with a misspelled rule id; specifying a rule for a language other than the one loaded; rule removed/renamed after a LanguageTool upgrade.

Understand the failure class

Background: Record Not Found Errors: "not found", RecordNotFound, and "was not found" — what they mean and how to fix them — this error's family across 28 libraries.

Related errors

• id is null for rule with name '
• Neither '<pattern>' tokens nor '<regexp>' is set in rule '
• Cannot activate rule '
• Rule '<ruleId>' not found for language <lang> (LanguageTool
• No rules are active. Please make sure your rule ids (<option

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/411526c5d8e080a0. Report an issue: GitHub.