apache/iceberg · error · IllegalArgumentException

Unsupported logical type: ${logicalType}

Error message

Unsupported logical type: ${logicalType}

What it means

SparkAvroWriter.primitive builds Avro value writers for a Spark primitive type; within a STRING branch it handles known logical types (decimal, uuid) and throws IllegalArgumentException for any other Avro logical type annotation it doesn't recognize.

Source

Thrown at spark/v4.2/spark/src/main/java/org/apache/iceberg/spark/data/SparkAvroWriter.java:142

      if (logicalType != null) {
        switch (logicalType.getName()) {
          case "date":
            // Spark uses the same representation
            return ValueWriters.ints();

          case "timestamp-micros":
            // Spark uses the same representation
            return ValueWriters.longs();

          case "decimal":
            LogicalTypes.Decimal decimal = (LogicalTypes.Decimal) logicalType;
            return SparkValueWriters.decimal(decimal.getPrecision(), decimal.getScale());

          case "uuid":
            return SparkValueWriters.uuids();

          default:
            throw new IllegalArgumentException("Unsupported logical type: " + logicalType);
        }
      }

      switch (primitive.getType()) {
        case NULL:
          return ValueWriters.nulls();
        case BOOLEAN:
          return ValueWriters.booleans();
        case INT:
          if (type instanceof ByteType) {
            return ValueWriters.tinyints();
          } else if (type instanceof ShortType) {
            return ValueWriters.shorts();
          }
          return ValueWriters.ints();
        case LONG:
          return ValueWriters.longs();
        case FLOAT:

View on GitHub (pinned to 86d9c8fc54)

Solutions

1. Upgrade the Iceberg runtime so the writer recognizes the logical type.
2. Adjust the Avro schema to drop the unsupported logical type annotation if the underlying primitive is what you intend.
3. Convert the data to a supported type before writing.

// verify Avro schema logical types are only decimal or uuid before writing
if (!Set.of("decimal", "uuid").contains(logicalTypeName)) throw new IllegalArgumentException("unsupported");

if ("string".equals(primitive.getType().getName()) && logicalType != null && !"decimal".equals(logicalType.getName()) && !"uuid".equals(logicalType.getName())) { /* unsupported */ }

try { write(dataset); } catch (IllegalArgumentException e) { if (e.getMessage().startsWith("Unsupported logical type")) { /* fix schema */ } else throw e; }

When it happens

Trigger: Writing Spark data to Iceberg Avro files when an Avro string primitive carries a logicalType name not in the supported set (only decimal and uuid are handled).

Common situations: Avro schemas with custom/less-common logical types (e.g. time-micros annotations on unexpected types) feeding the writer path; schema from a newer spec writer.

Related errors

• Unsupported type: {primitive}
• 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/144ce9c1e4b98076. Report an issue: GitHub.