stanfordnlp/CoreNLP · error · RuntimeIOException

slurpFile IO problem

Error message

slurpFile IO problem

What it means

slurpFileNoExceptions() wraps failures of slurpFile(filename, encoding) in a RuntimeIOException with message "slurpFile IO problem". It is thrown when reading the entire text of a file fails with an IOException (missing file, unreadable file, wrong encoding, etc.). The original IOException is chained as the cause, so check getCause() for the real reason.

Solutions

1. Verify the file path exists and is readable: new File(path).canRead() before calling, or print new File(path).getAbsolutePath() to check path resolution.
2. Inspect e.getCause() (the chained IOException) to see the underlying reason (FileNotFoundException vs UnsupportedEncodingException).
3. Check the encoding string is a valid Java charset name, or use the File overload without encoding (defaults to UTF-8 in recent versions).
4. If you want the checked exception instead, call IOUtils.slurpFile(filename, encoding) directly and handle IOException.

Example fix

// before
String text = IOUtils.slurpFileNoExceptions(cfgPath, "UTF-8");
// after
File f = new File(cfgPath);
if (!f.isFile() || !f.canRead()) {
  throw new IllegalArgumentException("Cannot read config: " + f.getAbsolutePath());
}
String text = IOUtils.slurpFileNoExceptions(f, StandardCharsets.UTF_8.name());

File f = new File(path);
if (!f.isFile()) throw new IllegalStateException("Not a file: " + f.getAbsolutePath());
if (!f.canRead()) throw new IllegalStateException("Not readable: " + f.getAbsolutePath());
Charset.forName(encoding); // validate charset name

try {
  String text = IOUtils.slurpFileNoExceptions(f, encoding);
} catch (RuntimeIOException e) {
  throw new IOException("Failed to slurp " + f.getAbsolutePath() + ": " + e.getCause(), e.getCause());
}

When it happens

Trigger: Calling IOUtils.slurpFileNoExceptions(filename, encoding) when slurpFile throws: the file does not exist, the path is a directory, the process lacks read permission, the stream cannot be opened, or the reader/decoder fails due to an invalid or unsupported encoding.

Common situations: Config files or corpus files specified with a wrong path or relative path resolved against an unexpected working directory; typo'd charset name (e.g. "utf8" typos are usually fine but "UTF_8" is not); files deleted or moved between existence-check and read; running as a user without read permission.

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

• edu.stanford.nlp.io.RuntimeIOException
• Error reading saved links
• error loading
• Could not read from float initial weight file
• Could not read from double initial weight file

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/df4a62bef7433847. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/io/IOUtils.java:1192

   */
  public static String slurpFile(String filename, String encoding)
          throws IOException {
    Reader r = readerFromString(filename, encoding);
    return IOUtils.slurpReader(r);
  }

  /**
   * Returns all the text in the given file with the given
   * encoding. If the file cannot be read (non-existent, etc.), then
   * the method throws an unchecked RuntimeIOException.  If the caller
   * is willing to tolerate missing files, they should catch that
   * exception.
   */
  public static String slurpFileNoExceptions(String filename, String encoding) {
    try {
      return slurpFile(filename, encoding);
    } catch (IOException e) {
      throw new RuntimeIOException("slurpFile IO problem", e);
    }
  }

  /**
   * Returns all the text in the given file
   *
   * @return The text in the file.
   */
  public static String slurpFile(String filename) throws IOException {
    return slurpFile(filename, defaultEncoding);
  }

  /**
   * Returns all the text at the given URL.
   */
  public static String slurpURLNoExceptions(URL u, String encoding) {
    try {
      return IOUtils.slurpURL(u, encoding);

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