apache/iceberg · error · IllegalArgumentException

Unsupported primitive type

Error message

Unsupported primitive type: <type>

What it means

Thrown by ParquetConversions.convertValue's outer default branch when the requested Iceberg primitive type has no Parquet-to-Iceberg value conversion implemented. The switch over the Iceberg type only handles known primitives; any other or unmapped type falls through to this error.

Solutions

1. Use a supported Iceberg primitive type in the converter call.
2. Upgrade Iceberg so the type is supported by ParquetConversions.
3. Convert nested/complex values through the dedicated readers (value readers/struct readers) instead of convertValue.

Example fix

// before
converter(parquetType, Types.NestedField.of(..., Types.StructType.get()))
// after
converter(parquetType, Types.IntegerType.get()) // or handle complex types with the standard readers

if (icebergType.isPrimitiveType()) {
  switch (icebergType.asPrimitiveType().typeId()) {
    case BOOLEAN: case INT: case LONG: case FLOAT: case DOUBLE: case DATE: case TIME:
    case TIMESTAMP: case STRING: case UUID: case FIXED: case BINARY: case DECIMAL: break;
    default: throw new IllegalArgumentException("Type not convertible: " + icebergType);
  }
}

boolean convertible(Type t) {
  return t.isPrimitiveType();
}

try {
  Object v = ParquetConversions.convertValue(parquetType, type, scale, value);
} catch (IllegalArgumentException e) {
  LOG.error("Unsupported type {} for Parquet conversion", type, e);
  throw e;
}

When it happens

Trigger: Passing an Iceberg type to convertValue that the converter does not support (e.g. a composite/nested type or a newer primitive added to the spec but not the converter), usually from converterFromParquet wiring.

Common situations: Custom read pipelines converting values manually; version skew where a new Iceberg type is read by an older converter; misuse of the public converter API with non-primitive types.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• Avro writer does not support variant types
• Byte stream split encoding is not supported for type " +…
• Cannot convert unknown primitive type
• Cannot decode dictionary of type
• Not a boolean column

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/bfdf3bb7a7287eb3. Report an issue: GitHub.

Appendix: source

Thrown at parquet/src/main/java/org/apache/iceberg/parquet/ParquetConversions.java:71

      case FIXED:
      case BINARY:
        return (T) ((Binary) value).toByteBuffer();
      case DECIMAL:
        int scale =
            ((DecimalLogicalTypeAnnotation) parquetType.getLogicalTypeAnnotation()).getScale();
        switch (parquetType.getPrimitiveTypeName()) {
          case INT32:
          case INT64:
            return (T) BigDecimal.valueOf(((Number) value).longValue(), scale);
          case FIXED_LEN_BYTE_ARRAY:
          case BINARY:
            return (T) new BigDecimal(new BigInteger(((Binary) value).getBytes()), scale);
          default:
            throw new IllegalArgumentException(
                "Unsupported primitive type for decimal: " + parquetType.getPrimitiveTypeName());
        }
      default:
        throw new IllegalArgumentException("Unsupported primitive type: " + type);
    }
  }

  static Function<Object, Object> converterFromParquet(
      PrimitiveType parquetType, Type icebergType) {
    Function<Object, Object> fromParquet = converterFromParquet(parquetType);
    if (icebergType != null) {
      if (icebergType.typeId() == Type.TypeID.LONG
          && parquetType.getPrimitiveTypeName() == PrimitiveType.PrimitiveTypeName.INT32) {
        return value -> ((Integer) fromParquet.apply(value)).longValue();
      } else if (icebergType.typeId() == Type.TypeID.DOUBLE
          && parquetType.getPrimitiveTypeName() == PrimitiveType.PrimitiveTypeName.FLOAT) {
        return value -> ((Float) fromParquet.apply(value)).doubleValue();
      } else if (icebergType.typeId() == Type.TypeID.UUID) {
        return binary -> UUIDUtil.convert(((Binary) binary).toByteBuffer());
      }
    }

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