apache/beam · error · java.lang.RuntimeException

DynamicMessage is not allowed for the standard…

Error message

DynamicMessage is not allowed for the standard ProtoSchemaProvider, use ProtoDynamicMessageSchema  instead.

What it means

The standard ProtoSchemaProvider cannot build a schema for DynamicMessage because field information lives in a runtime Descriptor rather than generated accessors. Beam throws this to steer users to ProtoDynamicMessageSchema, which handles descriptor-based messages.

Solutions

1. Use ProtoDynamicMessageSchema / the dynamic message schema provider for DynamicMessage types.
2. Switch the PCollection element type to a concrete generated Message class.
3. If dynamic parsing is not needed, use ProtoCoder or generated classes.

Example fix

// before
schemaRegistry.registerTypeDescriptor(DynamicMessage.class);
// after
new ProtoDynamicMessageSchema(descriptorForType).schemaFor(TypeDescriptor.of(DynamicMessage.class));

if (typeDescriptor.getRawType().equals(DynamicMessage.class)) {
  // route to ProtoDynamicMessageSchema instead
}

boolean isDynamic = DynamicMessage.class.equals(type.getRawType());

try { schema = protoSchema.schemaFor(type); } catch (RuntimeException e) { if (e.getMessage().contains("DynamicMessage")) schema = dynamicSchema.schemaFor(type); else throw e; }

When it happens

Trigger: Calling schemaFor (through checkForDynamicType) with TypeDescriptor.of(DynamicMessage.class), e.g. registering DynamicMessage in a Schema registry or creating a schema'd PCollection of DynamicMessage via the standard provider.

Common situations: Pipelines parsing protos from descriptors at runtime; code that switched from generated messages to DynamicMessage without updating schema configuration.

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

• Cannot create creator for
• Could not decode bytes as message
• Could not encode message as bytes
• Encountered UNSPECIFIED AtomicType
• Failed to decode Schema due to an error decoding Field…

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/e56ce76104e83c71. Report an issue: GitHub.

Appendix: source

Thrown at sdks/java/extensions/protobuf/src/main/java/org/apache/beam/sdk/extensions/protobuf/ProtoMessageSchema.java:154

        new ProtoMessageSchema(),
        TypeDescriptor.of(protoClass),
        bytes -> protoCoder.getParser().parseFrom(bytes));
  }

  // Other modules are not allowed to use non-vendored Message class
  @SuppressWarnings({
    "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
    "unchecked"
  })
  public static <T> SimpleFunction<Row, byte[]> getRowToProtoBytesFn(Class<T> clazz) {
    Class<Message> protoClass = ensureMessageType(clazz);
    return RowMessages.rowToBytesFn(
        new ProtoMessageSchema(), TypeDescriptor.of(protoClass), Message::toByteArray);
  }

  private <T> void checkForDynamicType(TypeDescriptor<T> typeDescriptor) {
    if (typeDescriptor.getRawType().equals(DynamicMessage.class)) {
      throw new RuntimeException(
          "DynamicMessage is not allowed for the standard ProtoSchemaProvider, use"
              + " ProtoDynamicMessageSchema  instead.");
    }
  }

  private static Class<Message> ensureMessageType(Class<?> clazz) {
    checkArgument(
        Message.class.isAssignableFrom(clazz),
        "%s is not a subtype of %s",
        clazz.getName(),
        Message.class.getSimpleName());
    return (Class<Message>) clazz;
  }
}

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