stanfordnlp/CoreNLP · error · IllegalArgumentException

Unknown argument

Error message

Unknown argument ${args[argIndex]}

What it means

A command-line argument parse failure in the ConvertGenderFile static main tool: it only accepts -input and -output flags (each with a value); any other token on the command line triggers this IllegalArgumentException, indicating a typo or unsupported flag.

Solutions

1. Only pass -input <file> and -output <file> arguments
2. Fix any misspelled flags
3. Check the tool's usage/main source for the accepted flag set

Example fix

// before
java ConvertGenderFile -in gender.txt -out gender.ser
// after
java ConvertGenderFile -input gender.txt -output gender.ser

List<String> allowed = Arrays.asList("-input", "-output");
for (int i = 0; i < args.length; i += 2) {
  if (!allowed.contains(args[i].toLowerCase())) throw new IllegalArgumentException("Unknown arg " + args[i]);
}

try {
  ConvertGenderFile.main(args);
} catch (IllegalArgumentException e) {
  System.err.println("Usage: ConvertGenderFile -input <file> -output <file>");
}

When it happens

Trigger: Running java edu.stanford.nlp.dcoref.util.ConvertGenderFile with an argument other than -input/-output, e.g. misspelled flags or extra positional arguments.

Common situations: Typo like -in instead of -input; passing flags copied from another CoreNLP tool; adding a stray filename without a flag.

Understand the failure class

Background: "Unknown argument", "Invalid value", and "must be one of": invalid CLI argument errors explained — this error's family across 35 libraries.

Related errors

• Invalid metricType
• Invalid sub score type
• Must specify input with -input
• Must specify output with -output
• is not a legal LogPrior.

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/c216562647c67606. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/dcoref/util/ConvertGenderFile.java:37

 *
 * @author John Bauer
 */
public class ConvertGenderFile {

  private ConvertGenderFile() {} // static class

  public static void main(String[] args) throws IOException {
    String input = null;
    String output = null;
    for (int argIndex = 0; argIndex < args.length; ) {
      if (args[argIndex].equalsIgnoreCase("-input")) {
        input = args[argIndex + 1];
        argIndex += 2;
      } else if (args[argIndex].equalsIgnoreCase("-output")) {
        output = args[argIndex + 1];
        argIndex += 2;
      } else {
        throw new IllegalArgumentException("Unknown argument " + args[argIndex]);
      }
    }

    if (input == null) {
      throw new IllegalArgumentException("Must specify input with -input");
    }

    if (output == null) {
      throw new IllegalArgumentException("Must specify output with -output");
    }

    Map<List<String>, Gender> genderNumber = Generics.newHashMap();

    BufferedReader reader = IOUtils.readerFromString(input);
    for (String line; (line = reader.readLine()) != null; ) {
      String[] split = line.split("\t");
      String[] countStr = split[1].split(" ");

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