stanfordnlp/CoreNLP · error · java.lang.IllegalArgumentException

Unknown argument

Error message

Unknown argument ${args[argIndex]}

What it means

CacheParseHypotheses.main() throws this IllegalArgumentException when an unrecognized argument is passed to its option parser. The tool only accepts flags such as -model, -output, and -numThreads; anything else is rejected.

Solutions

1. Restrict arguments to the supported flags: -model, -output, -numThreads
2. Fix the typo in the offending argument
3. Ensure every flag's value is present and properly quoted

Example fix

// before
java CacheParseHypotheses -model parser.gz -cacheFile out
// after
java CacheParseHypotheses -model parser.gz -output out

Set<String> allowed = Set.of("-model", "-output", "-numThreads");
for (String a : args) if (a.startsWith("-") && !allowed.contains(a)) throw new IllegalArgumentException("unsupported flag: " + a);

try { CacheParseHypotheses.main(args); } catch (IllegalArgumentException e) { System.err.println("Bad arguments: " + e.getMessage()); System.exit(1); }

When it happens

Trigger: Running CacheParseHypotheses with an unsupported flag, or a flag whose value was quoted incorrectly so the parser lands on the wrong token.

Common situations: Passing options borrowed from other dvparser main classes that this tool does not implement; typos in flag names like -model; missing values causing misalignment of the arg loop.

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

• Unknown argument
• Bad arguments after
• Must supply either a base parser model with -parser or a…
• Need to either train a new model, run the gradient check or…
• Expected a LexicalizedParser with a Reranker attached

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/14feb6dc8de85038. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/parser/dvparser/CacheParseHypotheses.java:229

        continue;
      }
      if (args[argIndex].equalsIgnoreCase("-output")) {
        output = args[argIndex + 1];
        argIndex += 2;
        continue;
      }
      if (args[argIndex].equalsIgnoreCase("-treebank")) {
        Pair<String, FileFilter> treebankDescription = ArgUtils.getTreebankDescription(args, argIndex, "-treebank");
        argIndex = argIndex + ArgUtils.numSubArgs(args, argIndex) + 1;
        treebanks.add(treebankDescription);
        continue;
      }
      if (args[argIndex].equalsIgnoreCase("-numThreads")) {
        numThreads = Integer.parseInt(args[argIndex + 1]);
        argIndex += 2;
        continue;
      }
      throw new IllegalArgumentException("Unknown argument " + args[argIndex]);
    }

    if (parserModel == null) {
      throw new IllegalArgumentException("Need to supply a parser model with -model");
    }
    if (output == null) {
      throw new IllegalArgumentException("Need to supply an output filename with -output");
    }
    if (treebanks.isEmpty()) {
      throw new IllegalArgumentException("Need to supply a treebank with -treebank");
    }

    log.info("Writing output to " + output);
    log.info("Loading parser model " + parserModel);
    log.info("Writing " + dvKBest + " hypothesis trees for each tree");

    LexicalizedParser parser = LexicalizedParser.loadModel(parserModel, "-dvKBest", Integer.toString(dvKBest));
    CacheParseHypotheses cacher = new CacheParseHypotheses(parser);

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