stanfordnlp/CoreNLP · error · RuntimeException

Invalid morphology string:

Error message

Invalid morphology string: 

What it means

MorphoFeatureSpecification.splitMorphString expects a morphological string of the form 'lemma^featureString' (split on the LEMMA_MARK separator '^'). It throws a RuntimeException when the string is non-empty but does not split into exactly two parts, i.e. the separator is missing or appears more than once.

Solutions

1. Ensure each morph string uses the '^' separator exactly once: 'lemma^features'
2. Fix malformed entries in the morpho input file
3. Pre-validate lines before calling splitMorphString
4. Check which LEMMA_MARK constant the loaded specification uses and match it in your data

Example fix

// before
splitMorphString(word, "courir VER:pres");
// after
splitMorphString(word, "courir^VER:pres");

if (morphStr != null && !morphStr.trim().isEmpty() && morphStr.split("\\^").length != 2) throw new IllegalArgumentException("Expected 'lemma^features': " + morphStr);

boolean isValidMorphString(String s) { return s == null || s.trim().isEmpty() || s.split("\\^").length == 2; }

try { pair = MorphoFeatureSpecification.splitMorphString(word, morphStr); } catch (RuntimeException e) { log.warn("Bad morph string, using NO_ANALYSIS: " + morphStr); pair = new Pair<>(word, MorphoFeatureSpecification.NO_ANALYSIS); }

When it happens

Trigger: Calling splitMorphString (directly or via addMorphologicalFeatures processing) with a morph string lacking the '^' separator, containing multiple '^', or being whitespace-with-content other than expected.

Common situations: Misformatted morphological analysis files where lemma and features are separated by a different character; hand-edited entries; preprocessed files that stripped the '^' character.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

• Dependencies should be for the format 'type(arg-idx…
• Expected left paren!
• Expected right paren!
• invalid format: ||
• Tag did not end with >

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/cf3f375953c7d455. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/international/morph/MorphoFeatureSpecification.java:63

    activeFeatures.add(feat);
  }
  
  public boolean isActive(MorphoFeatureType feat) { return activeFeatures.contains(feat); }
  
  public abstract List<String> getValues(MorphoFeatureType feat);
  
  public abstract MorphoFeatures strToFeatures(String spec);
  
  /**
   * Returns the lemma as pair.first() and the morph analysis as pair.second().
   */
  public static Pair<String,String> splitMorphString(String word, String morphStr) {
    if (morphStr == null || morphStr.trim().equals("")) {
      return new Pair<>(word, NO_ANALYSIS);
    }
    String[] toks = morphStr.split(Pattern.quote(LEMMA_MARK));
    if (toks.length != 2) {
      throw new RuntimeException("Invalid morphology string: " + morphStr);
    }
    return new Pair<>(toks[0], toks[1]);
  }
  
  
  @Override
  public String toString() { return activeFeatures.toString(); }
}

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