What causes "Dependency parsing is not implemented for Arabic" in stanfordnlp/CoreNLP?

Skip depparse for ArabicDocument instances (instanceof check before calling).

stanfordnlp/CoreNLP · error · IllegalArgumentException

Dependency parsing is not implemented for Arabic

Error message

Dependency parsing is not implemented for Arabic

What it means

ArabicDocument.runDepparse() throws IllegalArgumentException because dependency parsing is not implemented for Arabic in the stanford.nlp.simple API. Any call to Document.depparse() on an Arabic document reaches this stub and fails.

Solutions

Skip depparse for ArabicDocument instances (instanceof check before calling).
Use a supported language document for dependency parsing.
Train/wire an Arabic dependency model via the full CoreNLP annotator pipeline outside the simple API.

Example fix

// before
doc.depparse();
// after
if (!(doc instanceof ArabicDocument)) {
  doc.depparse();
}

Defensive patterns

Strategy: type-guard

Validate before calling

if (doc instanceof edu.stanford.nlp.simple.ArabicDocument) skipDepparse = true;

Type guard

boolean supportsDepparse(Document doc) { return !(doc instanceof edu.stanford.nlp.simple.ArabicDocument); }

Try / catch

try {
  doc.depparse();
} catch (IllegalArgumentException e) {
  if (e.getMessage() != null && e.getMessage().contains("not implemented")) {
    log.warn("Dependency parsing unavailable for this language, skipping");
  } else throw e;
}

Prevention

Check ArabicDocument javadoc for the list of unsupported operations before building pipelines.
Use per-language annotation requirement maps.
Never assume the neural dependency parser supports all languages.

When it happens

Trigger: Calling depparse() on an ArabicDocument, or running an annotator pipeline that requires dependency parse as a prerequisite (e.g. coref-style operations) on Arabic text.

Common situations: Multilingual pipelines applying the same annotation set to all languages; assuming the neural dependency parser supports Arabic.

Related errors

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/0d593baf0c4025d9. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/simple/ArabicDocument.java:89

   * No lemma annotator for Arabic -- set the lemma to be the word.
   *
   * @see Document#runLemma(Properties)
   */
  @Override
  protected Document runLemma(Properties props) {
    return mockLemma(props);
  }


  @Override
  protected Document runSentiment(Properties props) {
    throw new IllegalArgumentException("Sentiment analysis is not implemented for Arabic");
  }


  @Override
  protected Document runDepparse(Properties props) {
    throw new IllegalArgumentException("Dependency parsing is not implemented for Arabic");
  }

  @Override
  protected Document runNER(Properties props) {
    throw new IllegalArgumentException("NER is not implemented for Arabic");
  }


  @Override
  public Map<Integer, CorefChain> coref(Properties props) {
    throw new IllegalArgumentException("Coreference is not implemented for Arabic");
  }

}

View on GitHub (pinned to 1b7edd19c4)