stanfordnlp/CoreNLP · error · IllegalArgumentException

TaggedFileRecord argument

Error message

TaggedFileRecord argument ${arg} has an unexpected number of =s

What it means

createRecord() parses the semicolon-separated option list of a tagged file description as key=value pairs using split("=", 2). Each option argument must contain exactly one '='. An argument without '=' (or an empty one) can't be split into key and value, so IllegalArgumentException is thrown naming the offending argument.

Solutions

Fix the option string so every option is written as key=value, e.g. format=TSV,encoding=UTF-8.
Remove stray trailing commas or empty options from the semicolon-separated description.
Spell-check option keys; a value-only token usually means the '=' was dropped.

Example fix

// before
-tagger model.gz -testFile "data/test.txt,formatTSV"
// after
-tagger model.gz -testFile "data/test.txt,format=TSV"

Defensive patterns

Strategy: validation

Validate before calling

// Java: validate description options
boolean ok = arg.contains("=") && arg.indexOf('=') > 0 && arg.length() > arg.indexOf('=') + 1;

Prevention

Always write file description options as key=value.
Check for stray or trailing commas in semicolon-separated descriptions.
Unit-test your description strings before launching long training/tagging runs.

When it happens

Trigger: Including a bare token in the tagger's file description (e.g., "/path/file.txt,format=TEXT,badarg" or a trailing comma producing an empty argument) so that arg.split("=",2).length != 2.

Common situations: Typos in command-line testFile descriptions (missing '=' like "formatTEXT"), stray commas creating empty options, or copy-pasted configs where an option's value was deleted.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/14341efd5bb8251c. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/tagger/io/TaggedFileRecord.java:172

    String[] args = new String[pieces.length - 1];
    System.arraycopy(pieces, 0, args, 0, pieces.length - 1);
    String file = pieces[pieces.length - 1];
    Format format = Format.TEXT;
    String encoding = getEncoding(config);
    String tagSeparator = getTagSeparator(config);
    TreeTransformer treeTransformer = null;
    TreeNormalizer treeNormalizer = null;
    TreeReaderFactory trf = null;
    NumberRangesFileFilter treeRange = null;
    Predicate<Tree> treeFilter = null;
    Integer wordColumn = null, tagColumn = null;
    boolean comments = false;
    boolean skipMWT = false;

    for (String arg : args) {
      String[] argPieces = arg.split("=", 2);
      if (argPieces.length != 2) {
        throw new IllegalArgumentException("TaggedFileRecord argument " + arg +
                                           " has an unexpected number of =s");
      }
      if (argPieces[0].equalsIgnoreCase(FORMAT)) {
        format = Format.valueOf(argPieces[1]);
      } else if (argPieces[0].equalsIgnoreCase(ENCODING)) {
        encoding = argPieces[1];
      } else if (argPieces[0].equalsIgnoreCase(TAG_SEPARATOR)) {
        tagSeparator = argPieces[1];
      } else if (argPieces[0].equalsIgnoreCase(TREE_TRANSFORMER)) {
        treeTransformer = ReflectionLoading.loadByReflection(argPieces[1]);
      } else if (argPieces[0].equalsIgnoreCase(TREE_NORMALIZER)) {
        treeNormalizer = ReflectionLoading.loadByReflection(argPieces[1]);
      } else if (argPieces[0].equalsIgnoreCase(TREE_READER)) {
        trf = ReflectionLoading.loadByReflection(argPieces[1]);
      } else if (argPieces[0].equalsIgnoreCase(TREE_RANGE)) {
        String range = argPieces[1].replaceAll(":", ",");
        treeRange = new NumberRangesFileFilter(range, true);
      } else if (argPieces[0].equalsIgnoreCase(TREE_FILTER)) {

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