stanfordnlp/CoreNLP · error · RuntimeException

unable to find sentences in:

Error message

unable to find sentences in: 

What it means

TrueCaseAnnotator.annotate requires the input Annotation to contain sentence annotations (SentencesAnnotation), because classification runs per-token over sentence-split text. If no sentences are found, it throws this RuntimeException naming the annotation object.

Solutions

1. Run tokenization and sentence splitting before truecase: include 'tokenize,ssplit' before 'truecase' in the annotators list
2. If annotating manually, populate CoreAnnotations.SentencesAnnotation on the Annotation before calling annotate()
3. Use StanfordCoreNLP with requiredAnnotators so prerequisite stages are enforced
4. Verify an earlier annotator did not remove or fail to produce sentences

Example fix

// before
Properties props = new Properties();
props.setProperty("annotators", "truecase");
// after
Properties props = new Properties();
props.setProperty("annotators", "tokenize,ssplit,pos,truecase");

boolean hasSentences = annotation.get(CoreAnnotations.SentencesAnnotation.class) != null
    && !annotation.get(CoreAnnotations.SentencesAnnotation.class).isEmpty();
if (!hasSentences)
  throw new IllegalStateException("Run tokenize,ssplit before truecase");

try {
  trueCaseAnnotator.annotate(annotation);
} catch (RuntimeException e) {
  if (e.getMessage().startsWith("unable to find sentences")) {
    tokenizeAndSplitSentences(annotation);
    trueCaseAnnotator.annotate(annotation);
  } else throw e;
}

When it happens

Trigger: Calling truecase annotate() directly on an Annotation created from raw text without first running a tokenizer + WordsToSentencesAnnotator (ssplit), e.g. using a pipeline where 'truecase' is requested without 'tokenize,ssplit' preceding it.

Common situations: Building a minimal custom pipeline that omits ssplit, running truecase standalone in a test, or clearing/replacing sentences downstream of an earlier stage.

Related errors

• annotator " " requires annotation " ". The usual…
• Cannot run Natural Logic forward entailment without…
• Cannot run OpenIE without a parse tree!
• DocumentIterator exhausted.
• Error annotating

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/8abf3b894a730970. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/pipeline/TrueCaseAnnotator.java:122

      log.info("Adding true-case annotation...");
    }

    if (annotation.containsKey(CoreAnnotations.SentencesAnnotation.class)) {
      // classify tokens for each sentence
      for (CoreMap sentence: annotation.get(CoreAnnotations.SentencesAnnotation.class)) {
        List<CoreLabel> tokens = sentence.get(CoreAnnotations.TokensAnnotation.class);

        List<CoreLabel> output = this.trueCaser.classifySentence(tokens);

        for (int i = 0, size = tokens.size(); i < size; i++) {
          // add the truecaser tag to each token
          String neTag = output.get(i).get(CoreAnnotations.AnswerAnnotation.class);
          tokens.get(i).set(CoreAnnotations.TrueCaseAnnotation.class, neTag);
          setTrueCaseText(tokens.get(i));
        }
      }
    } else {
      throw new RuntimeException("unable to find sentences in: " + annotation);
    }
  }

  private void setTrueCaseText(CoreLabel l) {
    String trueCase = l.getString(CoreAnnotations.TrueCaseAnnotation.class);
    String text = l.word();
    String trueCaseText = text;

    switch (trueCase) {
      case "UPPER":
        trueCaseText = text.toUpperCase();
        break;
      case "LOWER":
        trueCaseText = text.toLowerCase();
        break;
      case "INIT_UPPER":
        trueCaseText = Character.toTitleCase(text.charAt(0)) + text.substring(1).toLowerCase();
        break;

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