stanfordnlp/CoreNLP · critical · RuntimeException

Missing property

Error message

Missing property: "${name}"

What it means

StanfordCoreNLP requires certain mandatory properties (e.g. annotators list) to build its pipeline. getRequiredProperty logs the missing key, prints the required-properties help, and throws a RuntimeException when props.getProperty(name) returns null. It is a fail-fast guard for missing pipeline configuration.

Solutions

1. Set the required property, typically props.setProperty("annotators", "tokenize,ssplit,pos,lemma,ner,parse,coref").
2. Verify the Properties object actually loaded content (check loadProperties return / file path).
3. Read the printed 'required properties' help output which lists exactly what is missing.
4. Use StanfordCoreNLP.getProperties()/defaults or copy a known-good StanfordCoreNLP.properties from the classpath.

Example fix

// before
Properties props = new Properties();
StanfordCoreNLP pipeline = new StanfordCoreNLP(props);
// after
Properties props = new Properties();
props.setProperty("annotators", "tokenize,ssplit,pos,lemma,ner");
StanfordCoreNLP pipeline = new StanfordCoreNLP(props);

if (props.getProperty("annotators") == null) {
  throw new IllegalArgumentException("props must define 'annotators' before creating StanfordCoreNLP");
}

try { pipeline = new StanfordCoreNLP(props); } catch (RuntimeException e) { if (e.getMessage().startsWith("Missing property")) { log.error("CoreNLP config incomplete: {}", e.getMessage()); } throw e; }

When it happens

Trigger: Calling new StanfordCoreNLP(props) (or getRequiredProperty indirectly via annoNames) where the Properties object lacks the 'annotators' key or another required key.

Common situations: Constructing a Properties object programmatically and forgetting to set 'annotators'; loading an empty or wrong properties file; renaming a key after a CoreNLP version upgrade.

Understand the failure class

Background: "is required", "must be set", "missing required field": configuration validation errors across open-source libraries — this error's family across 36 libraries.

Related errors

• Both parse.model and parse.executable properties must be…
• Can only create a model using this method if…
• Cannot create random word vectors for an unknown numHid
• Cannot determine annotation key for
• Cannot infer requirements for annotator

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/1c70783c2967df51. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/pipeline/StanfordCoreNLP.java:400

   *
   * @return A class which specifies the actual implementation of each of the annotators called
   *         when creating the annotator pool. The canonical annotators are defaulted to in
   *         {@link edu.stanford.nlp.pipeline.AnnotatorImplementations}.
   */
  protected AnnotatorImplementations getAnnotatorImplementations() {
    return new AnnotatorImplementations();
  }

  //
  // property-specific methods
  //

  private static String getRequiredProperty(Properties props, String name) {
    String val = props.getProperty(name);
    if (val == null) {
      logger.error("Missing property \"" + name + "\"!");
      printRequiredProperties(System.err);
      throw new RuntimeException("Missing property: \"" + name + '\"');
    }
    return val;
  }

  /**
   * Finds the properties file in the classpath and loads the properties from there.
   *
   * @return The found properties object (must be not-null)
   * @throws RuntimeException If no properties file can be found on the classpath
   */
  private static Properties loadPropertiesFromClasspath() {
    List<String> validNames = Arrays.asList("StanfordCoreNLP", "edu.stanford.nlp.pipeline.StanfordCoreNLP");
    for (String name : validNames) {
      Properties props = loadProperties(name);
      if (props != null) return props;
    }
    throw new RuntimeException("ERROR: Could not find properties file in the classpath!");
  }

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