apache/iceberg · error · IllegalStateException

Unknown type for int field. Type name: " + integer.getClass(

Error message

Unknown type for int field. Type name: " + integer.getClass().getName()

What it means

StructInternalRow.getInt extracts a Spark INTEGER/DATE int value from the underlying Iceberg struct field. It accepts Integer or LocalDate; any other stored Java type means the runtime object's class doesn't match the expected column type, so it throws IllegalStateException with the actual class name.

Source

Thrown at spark/v4.1/spark/src/main/java/org/apache/iceberg/spark/source/StructInternalRow.java:137

  public byte getByte(int ordinal) {
    return (byte) (int) struct.get(ordinal, Integer.class);
  }

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

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

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

  @Override
  public long getLong(int ordinal) {
    Object longVal = struct.get(ordinal, 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 {
      throw new IllegalStateException(
          "Unknown type for long field. Type name: " + longVal.getClass().getName());
    }

View on GitHub (pinned to 86d9c8fc54)

Solutions

1. Verify the expected Spark schema passed to the reader matches the actual Iceberg table schema for the int/date column
2. Check what class is printed in the message and fix the code that produces that type (e.g. wrap/convert Long to Integer, or use getLong for Long columns)
3. Update the Iceberg version if the underlying type-to-Java-class mapping changed for your type
4. Rebuild any cached table metadata after schema evolution

Example fix

// before
row.getInt(dateFieldOrdinal); // stored value is OffsetDateTime -> IllegalStateException
// after
// read the field with the accessor matching the actual stored type
long epochDay = row.getLong(ordinal); // or fix the producer to store LocalDate/Integer

Object v = struct.get(pos, javaClass);
if (!(v instanceof Integer) && !(v instanceof LocalDate)) {
  throw new IllegalStateException("expected Integer/LocalDate for int field, got " + v.getClass());
}

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

try { int i = row.getInt(ordinal); } catch (IllegalStateException e) { /* inspect e.getMessage() class name and fix the producer schema */ }

When it happens

Trigger: Reading a column whose Iceberg/Spark type mapping was wrong (e.g. the field actually holds Long, String, or BigDecimal) while Spark's expected schema declares an IntegerType/DateType at that ordinal — a struct-type/data mismatch between the provided schema and stored objects.

Common situations: Schema drift between table versions; supplying a wrong expected Spark schema in custom reads; custom Scan/GenericDataUtil conversions returning unexpected boxed types.

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 int field. Type name: ${integer.getClass().
• Unknown type for long field. Type name: ${longVal.getClass()
• Unknown type for binary field. Type name: ${bytes.getClass()
• Unknown type for int field. Type name: + integer.getClass().
• Unknown type for long field. Type name: " + longVal.getClass

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/234b528481669787. Report an issue: GitHub.