What causes "e" in stanfordnlp/CoreNLP?

Verify the input file path exists and is readable (ls -l / cat the file first)

e

Error message

What it means

TregexPattern's command-line main catches IOException from tree reading and logs it via log.warn(e), then continues exiting normally. It signals that reading the input trees (from a file or stdin) failed mid-way — the match counts printed reflect only the trees read before the failure.

Solutions

Verify the input file path exists and is readable (ls -l / cat the file first)
Run from the correct working directory or pass an absolute path to -f
Check file permissions and that the path is a regular file, not a directory
If strict behavior is wanted, copy the main logic and rethrow the IOException instead of warn-and-continue

Example fix

// before
java edu.stanford.nlp.trees.tregex.TregexPattern 'NP < NN' corpus.mrg
// after (file first verified)
ls -l corpus.mrg && java edu.stanford.nlp.trees.tregex.TregexPattern -f corpus.mrg 'NP < NN'

Defensive patterns

Strategy: validation

Validate before calling

File f = new File(args[filesIndex]);
if (!f.isFile() || !f.canRead()) throw new IllegalArgumentException("unreadable tree file: " + f);

Try / catch

try {
  // run TregexPattern matching
} catch (IOException e) {
  log.error("Failed reading input trees", e);
  System.exit(1);
}

Prevention

Check input file existence/readability before invoking TregexPattern
Use absolute paths or verify the JVM working directory
Prefer reading via an explicit Reader you control so IO failures surface with a clear filename

When it happens

Trigger: Running the Tregex main with -f/file arguments pointing at a missing or unreadable tree file, or the input stream ending with an IO error while PennTreeReader reads trees.

Common situations: Typo in the input filename; wrong working directory; piping an empty/closed stdin; file removed or permissions changed while running; reading a directory instead of a file.

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

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/24aedbef613f37e1. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/trees/tregex/TregexPattern.java:815

        int last = args.length - 1;
        errPW.println("Reading trees from file(s) " + args[last]);
        TreeReaderFactory trf = getTreeReaderFactory(treeReaderFactoryClassName);

        treebank = new DiskTreebank(trf, encoding);
        treebank.loadPath(args[last], extension, true);
      }
      TRegexTreeVisitor vis = new TRegexTreeVisitor(p, handles, encoding);

      treebank.apply(vis);
      Timing.endTime();
      if (TRegexTreeVisitor.printMatches) {
        errPW.println("There were " + vis.numMatches() + " matches in total.");
      }
      if (TRegexTreeVisitor.printNumMatchesToStdOut) {
        System.out.println(vis.numMatches());
      }
    } catch (IOException e) {
      log.warn(e);
    } catch (TregexParseException e) {
      errPW.println("Error parsing expression: " + args[0]);
      errPW.println("Parse exception: " + e);
    }
  }

  private static TreeReaderFactory getTreeReaderFactory(String treeReaderFactoryClassName) {
    TreeReaderFactory trf = new TRegexTreeReaderFactory();
    if (treeReaderFactoryClassName != null) {
      try {
        trf = (TreeReaderFactory) Class.forName(treeReaderFactoryClassName).getDeclaredConstructor().newInstance();
      } catch (Exception e) {
        throw new RuntimeException("Error occurred while constructing TreeReaderFactory: " + e);
      }
    }
    return trf;
  }

View on GitHub (pinned to 1b7edd19c4)