stanfordnlp/CoreNLP · error · IllegalArgumentException

Invalid value for useUnknownWordSignatures:

Error message

Invalid value for useUnknownWordSignatures:

What it means

EnglishUnknownWordModel's constructor validates the unknown word signature level (unknownLevel, inherited from UnknownWordModel defaults). If it falls below MIN_UNKNOWN or above MAX_UNKNOWN, the constructor throws IllegalArgumentException 'Invalid value for useUnknownWordSignatures: <level>'.

Solutions

  1. Set useUnknownWordSignatures to a supported value (within MIN_UNKNOWN..MAX_UNKNOWN, e.g. the default used by English parser models)
  2. Check the Options/LexOptions source of the unknownLevel and correct it before constructing the model
  3. If loading from a serialized model, regenerate options with a supported level

Example fix

// before
op.lexOptions.useUnknownWordSignatures = 9; // out of range
// after
op.lexOptions.useUnknownWordSignatures = 5; // supported level
Defensive patterns

Strategy: validation

Validate before calling

int level = op.lexOptions.useUnknownWordSignatures; if (level < MIN_UNKNOWN || level > MAX_UNKNOWN) throw new IllegalArgumentException("useUnknownWordSignatures out of range: " + level);

Type guard

boolean isValidUnknownLevel(int v) { return v >= MIN_UNKNOWN && v <= MAX_UNKNOWN; }

Try / catch

try { new EnglishUnknownWordModel(op, lex, wordIndex, tagIndex, unSeen); } catch (IllegalArgumentException e) { op.lexOptions.useUnknownWordSignatures = DEFAULT_UNKNOWN; retry(); }

Prevention

When it happens

Trigger: Building an EnglishUnknownWordModel when the configured unknown/signature level option (useUnknownWordSignatures) is outside the supported enum-like range, typically due to a bad value in parser options or a training file that recorded an invalid level.

Common situations: Hand-edited parser options or serialized option files carrying an unsupported unknownLevel; experimental settings pushing the level past the supported max.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/c84af6403c3dc42a. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/parser/lexparser/EnglishUnknownWordModel.java:71

  private static final boolean DEBUG_UWM = false;

  protected final boolean smartMutation;

  protected final int unknownSuffixSize;
  protected final int unknownPrefixSize;

  protected final String wordClassesFile;

  private static final int MIN_UNKNOWN = 0;
  private static final int MAX_UNKNOWN = 8;

  public EnglishUnknownWordModel(Options op, Lexicon lex,
                                 Index<String> wordIndex,
                                 Index<String> tagIndex,
                                 ClassicCounter<IntTaggedWord> unSeenCounter) {
    super(op, lex, wordIndex, tagIndex, unSeenCounter, null, null, null);
    if (unknownLevel < MIN_UNKNOWN || unknownLevel > MAX_UNKNOWN) {
      throw new IllegalArgumentException("Invalid value for useUnknownWordSignatures: " + unknownLevel);
    }
    this.smartMutation = op.lexOptions.smartMutation;
    this.unknownSuffixSize = op.lexOptions.unknownSuffixSize;
    this.unknownPrefixSize = op.lexOptions.unknownPrefixSize;
    wordClassesFile = op.lexOptions.wordClassesFile;
  }

  /**
   * This constructor creates an UWM with empty data structures.  Only
   * use if loading in the data separately, such as by reading in text
   * lines containing the data.
   */
  public EnglishUnknownWordModel(Options op, Lexicon lex,
                                 Index<String> wordIndex,
                                 Index<String> tagIndex) {
    this(op, lex, wordIndex, tagIndex, new ClassicCounter<>());
  }

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