apache/iceberg · error · IllegalStateException

Unknown type for int field. Type name:

Error message

Unknown type for int field. Type name: 

What it means

StructRowData.getInt converts an Iceberg struct field value into a Flink int. It supports Integer, LocalDate (as epoch days) and LocalTime (as milliseconds since midnight); anything else is unexpected and thrown as an IllegalStateException naming the actual Java class. This indicates the in-memory value does not match the declared Iceberg int field type.

Solutions

1. Check the actual class named in the message and align the writer so int fields contain Integer/LocalDate/LocalTime.
2. Verify the Flink row type and the Iceberg schema agree on the field being an int (IntegerType vs LongType etc.).
3. If you cannot fix the source data, wrap the read and convert the offending value yourself before it reaches StructRowData.

Example fix

// before: writer puts a long epoch-day value into an int DateType field
row.setField(pos, someLong);

// after: ensure the value is the expected class
row.setField(pos, (int) someLong); // or LocalDate.ofEpochDay(someLong)

// before reading
Object v = struct.getField(pos);
if (!(v instanceof Integer || v instanceof LocalDate || v instanceof LocalTime)) {
  throw new IllegalArgumentException("Unexpected class for int field: " + v.getClass());
}

boolean isIntCompatible(Object v) {
  return v instanceof Integer || v instanceof LocalDate || v instanceof LocalTime;
}

try {
  int value = rowData.getInt(pos);
} catch (IllegalStateException e) {
  // log e.getMessage() which names the offending class; convert or skip the field
}

When it happens

Trigger: Calling getInt(pos) on a StructRowData whose underlying field object is not an Integer, LocalDate, or LocalTime, e.g. a Long/String/BigDecimal placed in an int-typed field.

Common situations: Reading data written by a writer that stored the wrong Java class in an IntegerType field; custom data models that keep dates/times as different types than the Flink converters expect; schema evolution changing a field type without rewriting values.

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

• Unknown type for long field. Type name:
• errMsg(variant, "double")
• errMsg(variant, "int")
• errMsg(variant, "long")
• errMsg(variant, "timestamp")

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/c286e08b00fe7e60. Report an issue: GitHub.

Appendix: source

Thrown at flink/v2.3/flink/src/main/java/org/apache/iceberg/flink/data/StructRowData.java:130

  }

  @Override
  public short getShort(int pos) {
    return (short) (int) struct.get(pos, Integer.class);
  }

  @Override
  public int getInt(int pos) {
    Object integer = struct.get(pos, Object.class);

    if (integer instanceof Integer) {
      return (int) integer;
    } else if (integer instanceof LocalDate localDate) {
      return (int) localDate.toEpochDay();
    } else if (integer instanceof LocalTime) {
      return (int) (((LocalTime) integer).toNanoOfDay() / 1000_000);
    } else {
      throw new IllegalStateException(
          "Unknown type for int field. Type name: " + integer.getClass().getName());
    }
  }

  @Override
  public long getLong(int pos) {
    Object longVal = struct.get(pos, Object.class);

    if (longVal instanceof Long) {
      return (long) longVal;
    } else if (longVal instanceof OffsetDateTime) {
      return Duration.between(Instant.EPOCH, (OffsetDateTime) longVal).toNanos() / 1000;
    } else if (longVal instanceof LocalDate) {
      return ((LocalDate) longVal).toEpochDay();
    } else if (longVal instanceof LocalTime) {
      return ((LocalTime) longVal).toNanoOfDay();
    } else if (longVal instanceof LocalDateTime) {
      return Duration.between(Instant.EPOCH, ((LocalDateTime) longVal).atOffset(ZoneOffset.UTC))

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