stanfordnlp/CoreNLP · error · RuntimeException

Different chronology: c1=

Error message

Different chronology: c1=${c1}, c2=${c2}

What it means

combineMoreGeneralFields merges the more general fields of one Joda-Time Partial into another. It requires both Partials to be built on the exact same Chronology object (e.g. both ISOChronology); mixing chronologies would make field comparisons like isMoreGeneral meaningless, so the library throws a RuntimeException immediately when c1.equals(c2) fails.

Solutions

1. Ensure both Partials use the same chronology: rebuild one with p2.withChronology(p1.getChronology()) or construct both with the same DateTimeZone/chronology before calling.
2. Normalize to UTC or a single shared DateTimeZone when creating Partials (e.g. ISOChronology.getInstance(DateTimeZone.UTC)).
3. If chronologies must differ, convert values field-by-field into a new Partial on the target chronology instead of calling combineMoreGeneralFields directly.

Example fix

// before
Partial combined = JodaTimeUtils.combineMoreGeneralFields(p1, p2, null);
// after
if (!p1.getChronology().equals(p2.getChronology())) {
  p2 = p2.withChronology(p1.getChronology());
}
Partial combined = JodaTimeUtils.combineMoreGeneralFields(p1, p2, null);

if (!p1.getChronology().equals(p2.getChronology())) {
  p2 = p2.withChronology(p1.getChronology());
}

When it happens

Trigger: Calling JodaTimeUtils.combineMoreGeneralFields(p1, p2, mgf) (or its recursive overload) where p1 and p2 were created with different Chronologies, e.g. one from ISOChronology.getInstance() and another from a BuddhistChronology, GJChronology, or a chronology with a different time zone ( Chronologies with different zones are not equal).

Common situations: Mixing Partial objects parsed by different code paths that apply custom chronologies or zones; passing a Partial deserialized from an older serialization that restored a different chronology; constructing one Partial with DateTimeUtils default zone changed mid-run.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• Season start month is unknown
• Array must be sorted!
• Can only operate on preterminals
• Cannot find head word of empty span!
• Cannot read from null object!

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/63a59da13dda7354. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/time/JodaTimeUtils.java:447

        }
       // PeriodType.forFields(new DurationFieldType[]{dType});
       // return new Period(df.getUnitMillis(), PeriodType.forFields(new DurationFieldType[]{dType}));

      }
    }
    return null;
  }
  public static Partial combineMoreGeneralFields(Partial p1, Partial p2) {
    return combineMoreGeneralFields(p1, p2, null);
  }

  // Combines more general fields from p2 to p1
  public static Partial combineMoreGeneralFields(Partial p1, Partial p2, DateTimeFieldType mgf) {
    Partial p = p1;
    Chronology c1 = p1.getChronology();
    Chronology c2 = p2.getChronology();
    if (!c1.equals(c2)) {
      throw new RuntimeException("Different chronology: c1=" + c1 + ", c2=" + c2);
    }
    DateTimeFieldType p1MostGeneralField = null;
    if (p1.size() > 0) {
      p1MostGeneralField = p1.getFieldType(0);    // Assume fields ordered from most general to least....
    }
    if (mgf == null || (p1MostGeneralField != null && isMoreGeneral(p1MostGeneralField, mgf, c1))) {
      mgf = p1MostGeneralField;
    }
    for (int i = 0; i < p2.size(); i++) {
      DateTimeFieldType fieldType = p2.getFieldType(i);
      if (fieldType == DateTimeFieldType.year()) {
        if (p.isSupported(DateTimeFieldType.yearOfCentury())) {
          if (!p.isSupported(DateTimeFieldType.centuryOfEra())) {
            int yoc = p.get(DateTimeFieldType.yearOfCentury());
            int refYear = p2.getValue(i);
            int century = refYear / 100;
            int y2 = yoc + century*100;
            // TODO: Figure out which way to go

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