apache/iceberg · error · IllegalArgumentException

Unsupported type: {primitive}

Error message

Unsupported type: {primitive}

What it means

SparkAvroWriter's primitive() maps Avro primitive types to value writers; the default branch is unreachable for valid Avro primitives but guards against unknown/unexpected primitive enum values, throwing IllegalArgumentException. It indicates the Avro schema contains a primitive the writer cannot handle.

Source

Thrown at spark/v4.1/spark/src/main/java/org/apache/iceberg/spark/data/SparkAvroWriter.java:171

            return ValueWriters.tinyints();
          } else if (type instanceof ShortType) {
            return ValueWriters.shorts();
          }
          return ValueWriters.ints();
        case LONG:
          return ValueWriters.longs();
        case FLOAT:
          return ValueWriters.floats();
        case DOUBLE:
          return ValueWriters.doubles();
        case STRING:
          return SparkValueWriters.strings();
        case FIXED:
          return ValueWriters.fixed(primitive.getFixedSize());
        case BYTES:
          return ValueWriters.bytes();
        default:
          throw new IllegalArgumentException("Unsupported type: " + primitive);
      }
    }
  }
}

View on GitHub (pinned to 86d9c8fc54)

Solutions

1. Validate the Avro schema against the standard primitive set before writing
2. Upgrade Iceberg for newer Avro primitive support
3. Remap the field to a supported primitive type (e.g. BYTES/FIXED)
4. Check that the schema was not hand-edited or generated incorrectly

Set<Schema.Type> allowed = Set.of(STRING, INT, LONG, FLOAT, DOUBLE, BOOLEAN, FIXED, BYTES, NULL);
avroSchema.getFields().forEach(f -> {
  if (f.schema().getType() == Schema.Type.UNION) {
    f.schema().getTypes().forEach(t -> Preconditions.checkArgument(allowed.contains(t.getType()), t.getType()));
  } else Preconditions.checkArgument(allowed.contains(f.schema().getType()), f.schema().getType());
});

boolean supportedPrimitive(org.apache.avro.Schema s) {
  return s.getType() != UNION || s.getTypes().stream().allMatch(t -> t.getType() != UNION && isKnown(t));
}

try {
  writer.write(row);
} catch (IllegalArgumentException e) {
  if (e.getMessage().startsWith("Unsupported type")) { /* sanitize the Avro schema */ }
  else throw e;
}

When it happens

Trigger: Encountering an Avro primitive type outside the handled set (STRING, INT, LONG, FLOAT, DOUBLE, BOOLEAN, FIXED, BYTES, NULL) — typically only possible with a corrupted or non-standard schema, or a future Avro primitive type.

Common situations: Schema parsing anomalies from hand-written Avro schemas; forward-compatibility issues with newer Avro libraries introducing new primitives.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• Unsupported logical type: ${logicalType}
• Unsupported type: ${primitive}
• Unsupported type: %s
• Unsupported logical type:
• Unsupported type:

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/21cbd9d25f71dcff. Report an issue: GitHub.