apache/beam · error · IllegalArgumentException

No schema provided for getSchema(GenericRecord)

Error message

No schema provided for getSchema(GenericRecord)

What it means

AvroUtils.getSchema(Class) derives a Beam Schema from a Java/Avro class. For GenericRecord the Beam schema cannot be inferred from the class alone because it lives entirely in the Avro Schema object; calling without a schema is therefore a programming error and throws this IllegalArgumentException.

Source

Thrown at sdks/java/extensions/avro/src/main/java/org/apache/beam/sdk/extensions/avro/schemas/utils/AvroUtils.java:699

    }
  }

  @SuppressWarnings("unchecked")
  public static <T> SerializableFunction<Row, T> getFromRowFunction(Class<T> clazz) {
    return GenericRecord.class.equals(clazz)
        ? (SerializableFunction<Row, T>) getRowToGenericRecordFunction(null)
        : new AvroRecordSchema().fromRowFunction(TypeDescriptor.of(clazz));
  }

  public static @Nullable <T> Schema getSchema(
      Class<T> clazz, org.apache.avro.@Nullable Schema schema) {
    if (schema != null) {
      return schema.getType().equals(org.apache.avro.Schema.Type.RECORD)
          ? toBeamSchema(schema)
          : null;
    }
    if (GenericRecord.class.equals(clazz)) {
      throw new IllegalArgumentException("No schema provided for getSchema(GenericRecord)");
    }
    return new AvroRecordSchema().schemaFor(TypeDescriptor.of(clazz));
  }

  /** Returns a function mapping encoded AVRO {@link GenericRecord}s to Beam {@link Row}s. */
  public static SimpleFunction<byte[], Row> getAvroBytesToRowFunction(Schema beamSchema) {
    return new AvroBytesToRowFn(beamSchema);
  }

  private static class AvroBytesToRowFn extends SimpleFunction<byte[], Row> {
    private final AvroCoder<GenericRecord> coder;
    private final Schema beamSchema;

    AvroBytesToRowFn(Schema beamSchema) {
      org.apache.avro.Schema avroSchema = toAvroSchema(beamSchema);
      coder = AvroCoder.of(avroSchema);
      this.beamSchema = beamSchema;
    }

View on GitHub (pinned to 12126d8942)

Solutions

Use AvroUtils.schemaCoder(GenericRecord.class, avroSchema), passing the concrete Avro Schema.
If you have a typed Avro class (SpecificRecord), use that class instead of GenericRecord so the schema can be derived automatically.
Wire the Avro schema explicitly into coder registration for the pipeline (coder.setAvroSchema / schemaCoder overload).
Obtain the schema from the source (e.g. schema registry, data file footer) before constructing the coder.

Example fix

// before
Coder<GenericRecord> coder = AvroUtils.schemaCoder(GenericRecord.class); // throws
// after
Coder<GenericRecord> coder = AvroUtils.schemaCoder(GenericRecord.class, avroSchema);

Defensive patterns

Strategy: type-guard

Validate before calling

if (GenericRecord.class.equals(clazz)) {
  Objects.requireNonNull(avroSchema, "An Avro schema is required to get a Beam schema for GenericRecord");
}

Type guard

Optional<Schema> beamSchemaFor(Class<?> clazz, Schema avroSchema) {
  return GenericRecord.class.equals(clazz) && avroSchema != null
      ? Optional.of(AvroUtils.getSchema(GenericRecord.class, avroSchema))
      : Optional.empty();
}

Try / catch

try {
  return AvroUtils.schemaCoder(GenericRecord.class);
} catch (IllegalArgumentException e) {
  throw new IllegalStateException("Provide the AVRO schema: schemaCoder(GenericRecord.class, schema)", e);
}

Prevention

For GenericRecord, always use the schemaCoder overload that takes an Avro Schema.
Prefer SpecificRecord classes over GenericRecord when the schema is known at compile time.
Wire the Avro schema through pipeline options rather than resolving coders by class alone.

When it happens

Trigger: Calling AvroUtils.getSchema(GenericRecord.class) with schema == null, e.g. invoking schemaCoder(clazz) or schemaCoder(TypeDescriptor) for GenericRecord without supplying the Avro schema via schemaCoder(GenericRecord.class, avroSchema).

Common situations: Creating a Coder for GenericRecord records in a pipeline (CoderRegistry, DoFn output types) where Beam resolves coders by class only, so the required Avro schema is never provided; using getSchema in a custom coder without wiring the schema through.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/1f7119cc6dc4e680. Report an issue: GitHub.