languagetool-org/languagetool · error

Language

Error message

Language 

What it means

ConfusionRuleEvaluator's constructor asks the language for its language-model-based rules via language.getRelevantLanguageModelRules(...). If that returns null, the language has no language model support at all, so evaluation of confusion rules is impossible and the constructor throws 'Language X doesn't seem to support a language model'.

Source

Thrown at languagetool-dev/src/main/java/org/languagetool/dev/bigdata/ConfusionRuleEvaluator.java:74

  private static final List<Long> EVAL_FACTORS = Arrays.asList(10L, 100L, 1_000L, 10_000L, 100_000L, 1_000_000L, 10_000_000L);
  private static final int MAX_SENTENCES = 1000;

  private final Language language;
  private final boolean caseSensitive;
  private final boolean bothDirections;  // replace A by B and vice versa?
  private final ConfusionProbabilityRule rule;
  private final Map<Long, RuleEvalValues> evalValues = new HashMap<>();

  private boolean verbose = true;

  ConfusionRuleEvaluator(Language language, LanguageModel languageModel, boolean caseSensitive, boolean bothDirections) {
    this.language = language;
    this.caseSensitive = caseSensitive;
    this.bothDirections = bothDirections;
    try {
      List<Rule> rules = language.getRelevantLanguageModelRules(JLanguageTool.getMessageBundle(), languageModel, null);
      if (rules == null) {
        throw new RuntimeException("Language " + language + " doesn't seem to support a language model");
      }
      ConfusionProbabilityRule foundRule = null;
      for (Rule rule : rules) {
        if (rule.getId().equals(ConfusionProbabilityRule.RULE_ID)) {
          foundRule = (ConfusionProbabilityRule)rule;
          break;
        }
      }
      if (foundRule == null) {
        throw new RuntimeException("Language " + language + " has no language model rule with id " + ConfusionProbabilityRule.RULE_ID);
      } else {
        this.rule = foundRule;
      }
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
  }
  

View on GitHub (pinned to 2e990059ce)

Solutions

1. Use a language that supports language model rules (e.g. English, German, French) — check the module implements getRelevantLanguageModelRules with a non-null list.
2. Configure the language model: pass the model directory via JLanguageTool.withLanguageModel(new LanguageModel(dir)) or the -lm command line option before constructing the evaluator.
3. Verify the language module jar is on the classpath so the full language implementation (not a stub) is loaded.
4. Guard the evaluator construction: check getRelevantLanguageModelRules != null beforehand and skip unsupported languages.

Example fix

// before
ConfusionRuleEvaluator evaluator = new ConfusionRuleEvaluator(language, languageModel, caseSensitive, bothDirections);
// after
List<Rule> lmRules = language.getRelevantLanguageModelRules(JLanguageTool.getMessageBundle(), languageModel, null);
if (lmRules == null) {
  System.err.println("Skipping " + language + ": no language model support");
  return;
}
ConfusionRuleEvaluator evaluator = new ConfusionRuleEvaluator(language, languageModel, caseSensitive, bothDirections);

List<Rule> lmRules = language.getRelevantLanguageModelRules(JLanguageTool.getMessageBundle(), languageModel, null);
if (lmRules == null || lmRules.isEmpty()) {
  throw new UnsupportedOperationException(language + " has no language model rules; pass a supported language and configure -lm");
}

try {
  evaluator = new ConfusionRuleEvaluator(language, languageModel, caseSensitive, bothDirections);
} catch (RuntimeException e) {
  if (e.getMessage().contains("doesn't seem to support a language model")) {
    System.err.println("Skipping " + language + " (no LM support); supply -lm <modelDir> or a supported language");
  }
}

When it happens

Trigger: Constructing ConfusionRuleEvaluator with a Language whose getRelevantLanguageModelRules returns null — i.e. the language module does not implement language model rules (most languages), or the rules cannot be created because no language model was wired in.

Common situations: Running confusion-rule evaluation for a language like a small-language module that has no ConfusionProbabilityRule implementation; passing a demo/test Language object instead of a full module language; forgetting to configure the language model directory so the relevant rules are not registered.

Related errors

• List of language models is empty
• suppressMisspelledMatch must be a valid regex
• suppressMisspelledSuggestions must be a valid regex
• Missing key '${key}'
• Got no rule match:

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/dc963f538ee31cfd. Report an issue: GitHub.