stanfordnlp/CoreNLP · critical · RuntimeException

can't open file

Error message

can't open file: ${e.getMessage()}

What it means

The private CtbDict constructor loads the Chinese Treebank dictionary file from a hardcoded path on the NLP group's machines (/u/nlp/data/pos-tagger/dictionary). If that file cannot be read, the IOException is wrapped in a RuntimeException with the underlying message. This means the Chinese dictionary feature is unavailable in your environment.

Solutions

1. Create the directory /u/nlp/data/pos-tagger/dictionary and place the CTB dictionary file (defaultFilename) there, or symlink it to where your data lives
2. Retrain/run the tagger without Chinese dictionary features (do not enable dictionary-based extractors) so CtbDict is never instantiated
3. Patch readCtbDict to load the dictionary from a configurable path or classpath resource instead of the hardcoded absolute path
4. Check file permissions on the dictionary file so the JVM user can read it

Example fix

// before: hardcoded path fails
private CtbDict() {
  try {
    readCtbDict("/u/nlp/data/pos-tagger/dictionary" + '/' + defaultFilename);
  } catch(IOException e) {
    throw new RuntimeException("can't open file: " + e.getMessage());
  }
}
// after: configurable path with classpath fallback
private CtbDict() {
  String dir = System.getProperty("ctbDictPath", "/u/nlp/data/pos-tagger/dictionary");
  try {
    readCtbDict(dir + '/' + defaultFilename);
  } catch(IOException e) {
    throw new RuntimeException("can't open file: " + dir + '/' + defaultFilename, e);
  }
}

File dict = new File("/u/nlp/data/pos-tagger/dictionary/ChineseDictionary.txt");
if (!dict.canRead()) {
  throw new IllegalStateException("CTB dictionary missing/unreadable: " + dict);
}

try {
  CtbDict.getInstance();
} catch (RuntimeException e) {
  if (e.getMessage() != null && e.getMessage().startsWith("can't open file:")) {
    // disable Chinese dictionary features or supply the dictionary
  } else { throw e; }
}

When it happens

Trigger: Instantiating the singleton CtbDict (via CtbDict.getInstance()) when readCtbDict() fails to open the hardcoded dictionary path, e.g. the file does not exist or is unreadable on a machine outside the Stanford NLP network.

Common situations: Running the POS tagger with Chinese dictionary features on a server/cluster that lacks /u/nlp/data; a Stanford-internal path that external users never have; permission problems on the data directory.

Understand the failure class

Background: "File not found" and ENOENT errors: why libraries can't find a file that should exist — this error's family across 50 libraries.

Related errors

• Couldn't load classifier from
• File not found. Filename = " + filename
• Could not find inside
• Couldn't read function word file
• File not found:

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/ba623eeff61d8d42. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/tagger/maxent/CtbDict.java:30

public class CtbDict {

  private static final String defaultFilename = "ctb_dict.txt";
  private static CtbDict ctbDictSingleton;


  private static synchronized CtbDict getInstance() {
    if (ctbDictSingleton == null) {
      ctbDictSingleton = new CtbDict();
    }
    return ctbDictSingleton;
  }


  private CtbDict() {
    try {
      readCtbDict("/u/nlp/data/pos-tagger/dictionary" + '/' + defaultFilename);
    } catch(IOException e) {
      throw new RuntimeException("can't open file: " + e.getMessage());
      /* java sucks */
    }
  }


  public Map <String, Set <String>> ctb_pre_dict;
  public Map <String, Set <String>> ctb_suf_dict;


  private void readCtbDict(String filename) throws IOException {
    BufferedReader ctbDetectorReader = new BufferedReader(new InputStreamReader(new FileInputStream(filename), "GB18030"));
    String ctbDetectorLine;

    ctb_pre_dict = Generics.newHashMap();
    ctb_suf_dict = Generics.newHashMap();

    while ((ctbDetectorLine = ctbDetectorReader.readLine()) != null) {
      String[] fields = ctbDetectorLine.split("	");

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