stanfordnlp/CoreNLP · error · RuntimeException

No label for '" + text + "'

Error message

No label for '" + text + "'

What it means

ParseAndSetLabels attaches predicted labels to tree nodes using a text->label map; when a tree node's text has no entry in the labelMap and the MissingLabels policy is FAIL, it throws a RuntimeException with the unmatched text. This is a hard-fail mode so unmapped nodes are never silently mislabeled.

Solutions

  1. Add the missing text 'X' to the labels file so the map covers all inputs
  2. Run with a tolerant policy (-missingLabelsOptions defaultLabel=NONE or keepOriginal) if strict failure is not needed
  3. Normalize tokenization/casing so tree text matches label keys
  4. Diff the set of tree texts against the label map keys before running to find gaps

Example fix

// before
// java ParseAndSetLabels -labels labels.txt -missingLabels FAIL ... 
// after
// java ParseAndSetLabels -labels labels.txt -missingLabels defaultLabel=UNKNOWN ...
Defensive patterns

Strategy: validation

Validate before calling

java.util.Set<String> texts = collectTreeTexts(trees);
java.util.Set<String> keys = labelMap.keySet();
texts.removeAll(keys);
if (!texts.isEmpty()) throw new IllegalStateException("texts missing from label map: " + texts);

Try / catch

try {
  tool.run();
} catch (RuntimeException e) {
  if (e.getMessage() != null && e.getMessage().startsWith("No label for")) {
    System.err.println("Extend your labels file for: " + e.getMessage());
  }
  throw e;
}

Prevention

When it happens

Trigger: Running ParseAndSetLabels with -missingLabels FAIL (the strict default) while the labels file lacks an entry for a token that appears in the trees/sentences being processed — e.g. the quoted string in "No label for 'X'" names the missing text.

Common situations: Labels file built from a different corpus than the input trees; tokenization differences producing unseen surface forms; case/whitespace mismatches between keys and tree text; OOV words at test time.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/96c93d2b7c93dc2d. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/parser/tools/ParseAndSetLabels.java:74

    FAIL, DEFAULT, KEEP_ORIGINAL
  }

  private ParseAndSetLabels() {} // static methods

  public static void setLabels(Tree tree, Map<String, String> labelMap,
                               MissingLabels missing, String defaultLabel,
                               Set<String> unknowns) {
    if (tree.isLeaf()) {
      return;
    }
    String text = SentenceUtils.listToString(tree.yield());
    String label = labelMap.get(text);
    if (label != null) {
      tree.label().setValue(label);
    } else {
      switch (missing) {
      case FAIL:
        throw new RuntimeException("No label for '" + text + "'");
      case DEFAULT:
        tree.label().setValue(defaultLabel);
        unknowns.add(text);
        break;
      case KEEP_ORIGINAL:
        // do nothing
        break;
      default:
        throw new IllegalArgumentException("Unknown MissingLabels mode " + missing);
      }
    }
    for (Tree child : tree.children()) {
      setLabels(child, labelMap, missing, defaultLabel, unknowns);
    }
  }

  public static Set<String> setLabels(List<Tree> trees, Map<String, String> labelMap,
                                      MissingLabels missing, String defaultLabel) {

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