stanfordnlp/CoreNLP · error · IllegalArgumentException

Unknown argument " + args[argIndex]

Error message

Unknown argument " + args[argIndex]

What it means

ExternalEvaluate's CLI argument parser rejects any option it does not recognize. When neither a built-in flag nor any flag registered via curOptions (setOption) consumes the argument at argIndex, setOption returns the index unchanged and main throws IllegalArgumentException.

Solutions

1. Run with -h/help or read ExternalEvaluate javadoc to list valid flags
2. Check spelling of the flag against the source's accepted strings
3. Ensure each flag that takes a value has its value present so argIndex advances correctly
4. Wrap custom options via curOptions so setOption can consume them

Example fix

// before
java edu.stanford.nlp.sentiment.ExternalEvaluate -goldPath gold.txt -predic file.txt
// after
java edu.stanford.nlp.sentiment.ExternalEvaluate -goldPath gold.txt -predicted preds.txt

Set<String> valid = new HashSet<>(Arrays.asList("-gold","-predicted","-annotations","-model","-saveModel","-testPath"));
for (String a : args) if (a.startsWith("-") && !valid.contains(a.toLowerCase())) throw new IllegalArgumentException("Unknown argument " + a);

try { ExternalEvaluate.main(args); } catch (IllegalArgumentException e) { if (e.getMessage().startsWith("Unknown argument")) { printUsageAndExit(); } else { throw e; } }

When it happens

Trigger: Running ExternalEvaluate with a misspelled flag (e.g. '-gold' vs '-goldPath'), an option not registered in the passed Options object, or a stray positional token that the parser tries to interpret as a flag.

Common situations: Users copying command lines from older documentation after flag renames, forgetting a required -predicted/-gold value causing mis-parsing, or passing unknown extra args in shell scripts.

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

• TaggedFileRecord argument
• -threads [number]: was not given a valid number:
• Unknown argument:
• Unknown argument " + args[argIndex]
• Unknown argument " + args[argIndex]

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/b1db8a55f141c9c5. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/sentiment/ExternalEvaluate.java:72

   *
   * For example <br>
   * {@code java edu.stanford.nlp.sentiment.ExternalEvaluate annotatedTrees.txt predictedTrees.txt }
   */
  public static void main(String[] args) {
    RNNOptions curOptions = new RNNOptions();
    String goldPath = null;
    String predictedPath = null;
    for (int argIndex = 0; argIndex < args.length;) {
      if (args[argIndex].equalsIgnoreCase("-gold")) {
        goldPath = args[argIndex + 1];
        argIndex += 2;
      } else if (args[argIndex].equalsIgnoreCase("-predicted")) {
        predictedPath = args[argIndex + 1];
        argIndex += 2;
      } else {
        int newArgIndex = curOptions.setOption(args, argIndex);
        if (newArgIndex == argIndex) {
          throw new IllegalArgumentException("Unknown argument " + args[argIndex]);
        }
        argIndex = newArgIndex;
      }
    }
    if (goldPath == null) {
      log.info("goldPath not set. Exit.");
      System.exit(-1);

    }
    if (predictedPath == null) {
      log.info("predictedPath not set. Exit.");
      System.exit(-1);
    }
    // filterUnknown not supported because I'd need to know which sentences
    // are removed to remove them from predicted
    List<Tree> goldTrees = SentimentUtils.readTreesWithGoldLabels(goldPath);
    List<Tree> predictedTrees = SentimentUtils.readTreesWithPredictedLabels(predictedPath);
    ExternalEvaluate evaluator = new ExternalEvaluate(curOptions, predictedTrees);

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