stanfordnlp/CoreNLP · error · IllegalArgumentException

Please specify -input

Error message

Please specify -input

What it means

A required-argument check in the ConvertModels command-line tool: the -input property (path to the source model to convert) was not supplied in the properties parsed from args, so conversion cannot proceed.

Solutions

1. Add -input /path/to/source/model to the command
2. Fix the flag spelling so argsToProperties picks up 'input'
3. Verify the property key is exactly 'input' (no leading dashes in the properties map)

Example fix

// before
... -stage NEW -model SENTIMENT -output out.gz
// after
... -stage NEW -model SENTIMENT -input models/sentiment.ser.gz -output out.gz

java.nio.file.Path in = java.nio.file.Path.of(inputArg);
if (inputArg == null || !java.nio.file.Files.exists(in)) {
  throw new IllegalArgumentException("-input must point to an existing model file");
}

try {
  ConvertModels.main(args);
} catch (IllegalArgumentException e) {
  if (e.getMessage().equals("Please specify -input")) {
    System.err.println("Missing -input; usage: -input <modelPath> -output <modelPath>");
    System.exit(2);
  }
  throw e;
}

When it happens

Trigger: Running the converter without -input on the command line, or misspelling the flag (e.g. -in, --input) so argsToProperties never sees an 'input' key.

Common situations: Scripted conversion pipelines where the flag was dropped during refactoring, or copying an example command and omitting the path.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• Please specify -model, either SENTIMENT, DVPARSER…
• Please specify -output
• Please specify -stage, either OLD or NEW
• Conflicting properties. Multi-word rules file will be…
• Must specify a treebank to train from with -trainTreebank…

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/52889c90696c1eb6. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/neural/ConvertModels.java:390

  public static void main(String[] args) throws IOException, ClassNotFoundException, InstantiationException, NoSuchMethodException {
    Properties props = StringUtils.argsToProperties(args);

    final Stage stage;
    try {
      stage = Stage.valueOf(props.getProperty("stage").toUpperCase(Locale.ROOT));
    } catch (IllegalArgumentException | NullPointerException e) {
      throw new IllegalArgumentException("Please specify -stage, either OLD or NEW");
    }

    final Model modelType;
    try {
      modelType = Model.valueOf(props.getProperty("model").toUpperCase(Locale.ROOT));
    } catch (IllegalArgumentException | NullPointerException e) {
      throw new IllegalArgumentException("Please specify -model, either SENTIMENT, DVPARSER, EMBEDDING, COREF, FASTCOREF");
    }

    if (!props.containsKey("input")) {
      throw new IllegalArgumentException("Please specify -input");
    }

    if (!props.containsKey("output")) {
      throw new IllegalArgumentException("Please specify -output");
    }

    String inputPath = props.getProperty("input");
    String outputPath = props.getProperty("output");

    if (modelType == Model.SENTIMENT) {
      if (stage == Stage.OLD) {
        SentimentModel model = SentimentModel.loadSerialized(inputPath);
        ObjectOutputStream out = IOUtils.writeStreamFromString(outputPath);
        writeSentiment(model, out);
        out.close();
      } else {
        ObjectInputStream in = IOUtils.readStreamFromString(inputPath);
        SentimentModel model = readSentiment(in);

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