languagetool-org/languagetool · error · RuntimeException

Could not create LanguageTool instance for language <languag

Error message

Could not create LanguageTool instance for language <language>

What it means

Main.changeLanguage builds a MultiThreadedJLanguageTool for the requested language and selects rules; any Exception there is rethrown as this RuntimeException. It means the LanguageTool instance for the given language code could not be constructed or its rules could not be selected.

Source

Thrown at languagetool-commandline/src/main/java/org/languagetool/commandline/Main.java:362

      String fileContents = readerToString(reader);
      if (xmlFiltering) {
        return filterXML(fileContents);
      } else {
        return fileContents;
      }
    }
  }

  private void changeLanguage(Language language, Language motherTongue,
                              List<String> disabledRules, List<String> enabledRules) {
    try {
      lt = new MultiThreadedJLanguageTool(language, motherTongue);
      Tools.selectRules(lt, disabledRules, enabledRules, true);
      if (options.isVerbose()) {
        lt.setOutput(System.err);
      }
    } catch (Exception e) {
      throw new RuntimeException("Could not create LanguageTool instance for language " + language, e);
    }
  }

  @FunctionalInterface
  interface SystemExitHandler {
    void exit(int status);
    SystemExitHandler DEFAULT = System::exit;
  }

  static SystemExitHandler exitHandler = SystemExitHandler.DEFAULT;

  /**
   * Command line tool to check plain text files.
   */
  public static void main(String[] args) throws IOException, ParserConfigurationException, SAXException {
    JnaTools.setBugWorkaroundProperty();
    CommandLineParser commandLineParser = new CommandLineParser();
    CommandLineOptions options = null;

View on GitHub (pinned to 2e990059ce)

Solutions

1. Check the 'Caused by' exception for the real initialization failure.
2. Verify the language code with `languagetool --list` or the supported-languages list for your version.
3. Remove/verify --enable and --disable rule ids; confirm they exist for the chosen language.
4. Reinstall/upgrade LanguageTool if language resources are missing from the distribution.

Example fix

// before
languagetool -l eng -c UTF-8 file.txt
// after
languagetool -l en-US -c UTF-8 file.txt

Language lang = Languages.getLanguageForShortCode(langCode); // throws early if unsupported
// also verify rule ids exist:
// lt.getRuleForId(...) or check --list output before running

try {
  Language lang = Languages.getLanguageForShortCode(code);
} catch (IllegalArgumentException e) {
  System.err.println("Unsupported language code: " + code);
  System.exit(2);
}

When it happens

Trigger: Calling the CLI with a -l/--language value whose Language instance fails initialization, or with --disable/--enable rule ids that make Tools.selectRules throw (e.g. a rule id referencing something invalid), or mother-tongue lookup failing.

Common situations: Unsupported or misspelled language code on the command line; corrupted/incomplete language resource deployment; enabling/disabling rules that don't exist for that language in that version.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• Could not check text in file <file>
• Could not activate rules
• Could not load language model capable rules.
• WrongParameterNumberException
• Unknown level '<level>' - currently, only 'PICKY' is support

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/c3e232bf7035f80a. Report an issue: GitHub.