stanfordnlp/CoreNLP · error · RuntimeIOException

propFileToProperties could not read properties file: " +…

Error message

propFileToProperties could not read properties file: " + filename

What it means

StringUtils.propFileToProperties loads a properties file from disk. If the load throws IOException, it is rethrown as RuntimeIOException('propFileToProperties could not read properties file: <filename>'), indicating the file could not be opened or read.

Solutions

1. Confirm the filename/path exists and is readable before calling (new File(filename).canRead())
2. Use an absolute path or resolve the path relative to a known base directory
3. If the file is a classpath resource, load it via getResourceAsStream instead of propFileToProperties

Example fix

// before
Properties p = StringUtils.propFileToProperties("config.properties"); // not in cwd
// after
File f = new File("config.properties");
if (!f.canRead()) throw new IllegalStateException("Missing config: " + f.getAbsolutePath());
Properties p = StringUtils.propFileToProperties(f.getAbsolutePath());

File f = new File(filename);
if (!f.isFile() || !f.canRead()) throw new IllegalStateException("Missing properties file: " + f.getAbsolutePath());

try {
  Properties p = StringUtils.propFileToProperties(filename);
} catch (RuntimeIOException e) {
  log.error("Cannot load properties: " + e.getMessage());
  p = new Properties(); // or abort
}

When it happens

Trigger: Calling StringUtils.propFileToProperties(filename) with a path that does not exist, is a directory, or cannot be read due to permissions or I/O errors.

Common situations: Config file not shipped with the application; relative path resolved against an unexpected working directory; file deleted between check and read in CI; wrong resource path when intending to load from the classpath instead of the filesystem.

Understand the failure class

Background: "failed to read file", EACCES, ENOENT and "could not read <path>" errors: when a program can't read a file from disk — this error's family across 49 libraries.

Related errors

• Error reading threshold file
• IOException reading CEDict from file
• argsToProperties could not read properties file: " + file
• Error loading classifier from
• edu.stanford.nlp.io.RuntimeIOException

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/9c28ec7cfddf4ed1. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/util/StringUtils.java:1098

   * something not implemented in the {@code load()} method.
   *
   * @param filename A properties file to read
   * @return The corresponding Properties object
   */
  public static Properties propFileToProperties(String filename) {
    try {
      InputStream is = new BufferedInputStream(new FileInputStream(filename));
      Properties result = new Properties();
      result.load(is);
      // trim all values
      for (String propKey : result.stringPropertyNames()){
        String newVal = result.getProperty(propKey);
        result.setProperty(propKey,newVal.trim());
      }
      is.close();
      return result;
    } catch (IOException e) {
      throw new RuntimeIOException("propFileToProperties could not read properties file: " + filename, e);
    }
  }

  /**
   * This method converts a comma-separated String (with whitespace
   * optionally allowed after the comma) representing properties
   * to a Properties object.  Each property is "property=value".  The value
   * for properties without an explicitly given value is set to "true". This can be used for a 2nd level
   * of properties, for example, when you have a commandline argument like "-outputOptions style=xml,tags".
   */
  public static Properties stringToProperties(String str) {
    Properties result = new Properties();
    return stringToProperties(str, result);
  }

  /**
   * This method updates a Properties object based on
   * a comma-separated String (with whitespace

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