stanfordnlp/CoreNLP · error · Error

Attribute already defined

Error message

Attribute already defined: ${attr.image}

What it means

Similar to the attribute-match check, this parser production parses simple attribute assignments (no match-value concatenation) and throws 'Attribute already defined: <attr>' when the same attribute key is assigned twice in one attribute block. The map check at line 1919 rejects the second assignment.

Solutions

1. Delete the duplicate attribute assignment or keep only the intended value.
2. If multiple values are needed, use a regex or disjunction in one attribute value.
3. Lint rule files for duplicate keys before loading them into the annotator.
4. Fix the generating code if rules are produced programmatically.

Example fix

// before
String node = "{ word:\"foo\" word:\"bar\" }";
// after
String node = "{ word:/foo|bar/ }";

java.util.Set<String> seen = new java.util.HashSet<>();
for (String line : attributeLines) {
  String key = line.split(":", 2)[0].trim();
  if (!seen.add(key)) throw new IllegalStateException("Attribute assigned twice: " + key);
}

try {
  attrs = parser.parseAttributeList(text);
} catch (Error e) {
  if (e.getMessage() != null && e.getMessage().startsWith("Attribute already defined")) {
    throw new IllegalArgumentException("Duplicate attribute assignment: " + e.getMessage(), e);
  }
  throw e;
}

When it happens

Trigger: Parsing an attribute list such as '{ word:"foo" word:"bar" }' where an attribute key is set more than once in the same specification.

Common situations: Generated or machine-merged TokensRegex rules emitting duplicate attribute assignments; developers duplicating a line when editing rules by hand.

Understand the failure class

Background: Conflicting config options: "cannot be used together" — configuration validation errors across open-source libraries — this error's family across 162 libraries.

Related errors

• Attribute match already defined
• Field already defined:
• Attribute match already defined:
• Attribute already defined:
• Unknown sequence pattern variable

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/050467552cc12f2d. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/ling/tokensregex/parser/TokenSequenceParser.java:1919

    case STR:{
      value = RelaxedStringToken();
      break;
      }
    case NONNEGINT:
    case INT:
    case REAL:{
      value = NumberToken();
      break;
      }
    default:
      jj_la1[65] = jj_gen;
      jj_consume_token(-1);
      throw new ParseException();
    }
if (value != null) { str = value.image; }
              if (attr != null && str != null)  {
                if (attributes.containsKey(attr.image)) {
                {if (true) throw new Error("Attribute already defined: " + attr.image);}
                }
                attributes.put(attr.image, str);
              }
          {if ("" != null) return attributes;}
    throw new Error("Missing return statement in function");
}

  final public Token NumberToken() throws ParseException {Token value = null;
    switch ((jj_ntk==-1)?jj_ntk_f():jj_ntk) {
    case NONNEGINT:{
      value = jj_consume_token(NONNEGINT);
      break;
      }
    case INT:{
      value = jj_consume_token(INT);
      break;
      }
    case REAL:{

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