stanfordnlp/CoreNLP · error · RuntimeException

Cannot initialize logger!

Error message

Cannot initialize logger!

What it means

CorefSystem.initLogger throws RuntimeException("Cannot initialize logger!") when java.util.logging FileHandler cannot attach a handler to logFileName — a SecurityException (security manager denies file logging) or IOException (path unwritable/invalid).

Solutions

1. Set the coref log file property to an absolute path in a writable directory and create parent dirs first
2. Check file write permissions on the log directory (chmod / run as appropriate user)
3. If a SecurityManager is active, grant FileHandler permissions or use console logging instead
4. Wrap or reconfigure java.util.logging to log to stdout in restricted environments

Example fix

// before
props.setProperty("coref.logFile", "logs/coref.log"); // logs/ doesn't exist
// after
File logDir = new File("/tmp/coref-logs");
logDir.mkdirs();
props.setProperty("coref.logFile", new File(logDir, "coref.log").getAbsolutePath());

File logFile = new File(logFileName);
File parent = logFile.getAbsoluteFile().getParentFile();
if (parent != null && !parent.isDirectory() && !parent.mkdirs()) {
  throw new IllegalStateException("Cannot create log dir: " + parent);
}
if (!logFile.getParentFile().canWrite()) {
  throw new IllegalStateException("Log dir not writable: " + parent);
}

try {
  system.runOnConll(props);
} catch (RuntimeException e) {
  if ("Cannot initialize logger!".equals(e.getMessage())) {
    logger.log(Level.SEVERE, "Logger init failed; check log path/permissions", e.getCause());
  } else throw e;
}

When it happens

Trigger: initLogger called (from runOnConll) with a logFileName in a nonexistent directory, a read-only location, or blocked by a SecurityException from a security manager.

Common situations: Log path points to a non-writable directory under the working dir; running in a sandboxed/containerized environment with restricted file access; logFileName containing invalid path characters or a locked file.

Understand the failure class

Background: "failed to write file", "Could not save figure", "Error saving remote file" — file write failed: causes and fixes across languages and libraries — this error's family across 38 libraries.

Related errors

• Error creating data exporter
• RuntimeIOException wrapping IOException
• Serializing classifier to
• Could not create directory <tgtDir.getAbsolutePath()>
• cp: could not list files in source

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/4fdd48bf074a2294. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/coref/CorefSystem.java:85

      CorefUtils.removeSingletonClusters(document);
    }
    CorefUtils.checkForInterrupt();

    Map<Integer, CorefChain> result = Generics.newHashMap();
    for (CorefCluster c : document.corefClusters.values()) {
      result.put(c.clusterID, new CorefChain(c, document.positions));
    }
    ann.set(CorefCoreAnnotations.CorefChainAnnotation.class, result);
  }

  public void initLogger(Logger logger, String logFileName) {
      try {
          FileHandler fh = new FileHandler(logFileName, false);
          logger.addHandler(fh);
          logger.setLevel(Level.FINE);
          fh.setFormatter(new NewlineLogFormatter());
      } catch (SecurityException | IOException e) {
          throw new RuntimeException("Cannot initialize logger!", e);
      }
  }

  public void runOnConll(Properties props) throws Exception {
    File f = new File(CorefProperties.conllOutputPath(props));
    if (! f.exists()) {
      f.mkdirs();
    }
    String timestamp = Calendar.getInstance().getTime().toString().replaceAll("\\s", "-").replaceAll(":", "-");
    String baseName = CorefProperties.conllOutputPath(props) + timestamp;
    String goldOutput = baseName + ".gold.txt";
    String beforeCorefOutput = baseName + ".predicted.txt";
    String afterCorefOutput = baseName + ".coref.predicted.txt";
    PrintWriter writerGold = new PrintWriter(new FileOutputStream(goldOutput));
    PrintWriter writerBeforeCoref = new PrintWriter(new FileOutputStream(beforeCorefOutput));
    PrintWriter writerAfterCoref = new PrintWriter(new FileOutputStream(afterCorefOutput));

    Logger logger = Logger.getLogger(CorefSystem.class.getName());

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