apache/beam · error · RuntimeException

Unable to generate a getter for class

Error message

Unable to generate a getter for class ${clazz} with schema ${schema}

What it means

After generating the accessor bytecode, AvroByteBuddyUtils instantiates the generated class; any InstantiationException/IllegalAccessException/NoSuchMethodException/InvocationTargetException during that instantiation is rethrown as RuntimeException. It indicates the generated getter/creator class could not be constructed for the given class+schema pair.

Solutions

Check the suppressed/underlying exception on the runtime error for the real reflective failure cause
Regenerate the Avro class from the current schema so bytecode matches
Disable ByteBuddy optimization (AvroUtils/AvroByteBuddyUtils toggle) to use reflection fallback
Verify JDK/Beam version compatibility for ByteBuddy

Example fix

null

Defensive patterns

Strategy: try-catch

Try / catch

try { return AvroByteBuddyUtils.getTypeCreator(clazz, schema); } catch (RuntimeException e) { return reflectivelyCreate(clazz, schema); }

Prevention

Check the exception's suppressed causes to find the real reflective failure
Confirm the class has accessible constructors in the executing classloader
Test ByteBuddy generation on the target JDK before deploying
Use reflection fallback when running under restricted module systems

When it happens

Trigger: getCreator/createCreator hitting reflective instantiation failure — typically because the target class cannot be instantiated in the current classloader context (abstract class, missing no-arg path, restricted module access, or Java module/JDK incompatibility with ByteBuddy generation).

Common situations: Running on newer JDKs where ByteBuddy-generated classes fail reflective construction, classes with private/absent constructors, or mismatched schema causing bad generated bytecode parameters.

Related errors

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/eddd644170f0427b. Report an issue: GitHub.

Appendix: source

Thrown at sdks/java/extensions/avro/src/main/java/org/apache/beam/sdk/extensions/avro/schemas/utils/AvroByteBuddyUtils.java:107

              .with(new InjectPackageStrategy(clazz))
              .subclass(SchemaUserTypeCreator.class)
              .method(ElementMatchers.named("create"))
              .intercept(construct);

      return builder
          .visit(new AsmVisitorWrapper.ForDeclaredMethods().writerFlags(ClassWriter.COMPUTE_FRAMES))
          .make()
          .load(
              ReflectHelpers.findClassLoader(clazz.getClassLoader()),
              getClassLoadingStrategy(clazz))
          .getLoaded()
          .getDeclaredConstructor()
          .newInstance();
    } catch (InstantiationException
        | IllegalAccessException
        | NoSuchMethodException
        | InvocationTargetException e) {
      throw new RuntimeException(
          "Unable to generate a getter for class " + clazz + " with schema " + schema);
    }
  }

  private static StackManipulation readAndConvertParameter(
      Class<?> constructorParameterType, int index) {
    TypeConversionsFactory typeConversionsFactory = new AvroUtils.AvroTypeConversionFactory();

    // The types in the AVRO-generated constructor might be the types returned by Beam's Row class,
    // so we have to convert the types used by Beam's Row class.
    // We know that AVRO generates constructor parameters in the same order as fields
    // in the schema, so we can just add the parameters sequentially.
    TypeConversion<Type> convertType = typeConversionsFactory.createTypeConversion(true);

    // Map the AVRO-generated type to the one Beam will use.
    ForLoadedType convertedType =
        new ForLoadedType((Class) convertType.convert(TypeDescriptor.of(constructorParameterType)));

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