apache/beam · error · RuntimeException

Could not find a way to create AutoValue class

Error message

Could not find a way to create AutoValue class <descriptor>

What it means

AutoValueSchema.schemaTypeCreator needs a way to construct instances of the AutoValue class: either a generated Builder or a package-private constructor in the generated AutoValue_Foo class. When getConstructorCreator returns null for both, Beam cannot map rows back into the class and throws this error.

Solutions

1. Verify the class is annotated @AutoValue and AutoValue_Foo is generated (check target/generated-sources or build output).
2. Clean rebuild to ensure annotation processing ran; enable annotationProcessorPaths in Maven/Gradle if missing.
3. Add an explicit @AutoValue.Builder to the class so Beam can use the builder creator path.
4. Avoid private/nested or shaded AutoValue classes for schema rows.

Example fix

// before
public abstract class Foo { public abstract String getName(); }

// after
@AutoValue public abstract class Foo {
  public abstract String getName();
  @AutoValue.Builder public abstract static class Builder {}
}

if (!targetType.isAnnotationPresent(AutoValue.class)) throw new IllegalStateException(targetType + " is not an @AutoValue class");

static boolean hasAutoValueImplementation(Class<?> c) {
  try { Class.forName(c.getName() + "$"); return false; } // not an AutoValue shape
  catch (ClassNotFoundException e) { }
  try { Class.forName(c.getName() + "$Builder"); return true; }
  catch (ClassNotFoundException e) { return false; } // relies on ctor path
}

try { schema = Schema.of(MyAutoValue.class); }
catch (RuntimeException e) {
  if (e.getMessage().contains("Could not find a way to create AutoValue class")) {
    throw new IllegalStateException("Ensure @AutoValue processing ran and a Builder or ctor exists", e);
  } throw e;
}

When it happens

Trigger: Using AutoValueSchema for a type whose generated AutoValue_ class exposes neither a builder nor a constructor the creator-factory lookup recognizes — e.g. the class isn't actually an @AutoValue class (descriptor points at the abstract class), code generation failed, or beam-schemas can't see the generated constructor via the AbstractGetterTypeSupplier.

Common situations: Forgetting the @AutoValue annotation so no AutoValue_Foo class was generated; annotation processing disabled in the build; nested/private AutoValue classes; shaded or relocated generated classes invisible at runtime; using interfaces annotated @AutoValue incorrectly.

Related errors

• Unable to generate a creator for class
• Unexpected null number for
• A schema is required to write non-schema'd data.
• All dicts in batch must have the same keys. extra keys
• An explicit schema is required to write non-schema'd…

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/03ddf425f1ea0dfb. Report an issue: GitHub.

Appendix: source

Thrown at sdks/java/core/src/main/java/org/apache/beam/sdk/schemas/AutoValueSchema.java:135

          new DefaultTypeConversionsFactory());
    }

    // Try to find a generated builder class. If one exists, use that to generate a
    // SchemaTypeCreator for creating AutoValue objects.
    SchemaUserTypeCreator creatorFactory =
        AutoValueUtils.getBuilderCreator(
            targetTypeDescriptor, schema, AbstractGetterTypeSupplier.INSTANCE);
    if (creatorFactory != null) {
      return creatorFactory;
    }

    // If there is no builder, there should be a package-private constructor in the generated
    // class. Use that for creating AutoValue objects.
    creatorFactory =
        AutoValueUtils.getConstructorCreator(
            targetTypeDescriptor, schema, AbstractGetterTypeSupplier.INSTANCE);
    if (creatorFactory == null) {
      throw new RuntimeException(
          "Could not find a way to create AutoValue class " + targetTypeDescriptor);
    }

    return creatorFactory;
  }

  @Override
  public <T> @Nullable Schema schemaFor(TypeDescriptor<T> typeDescriptor) {
    return JavaBeanUtils.schemaFromJavaBeanClass(
        typeDescriptor, AbstractGetterTypeSupplier.INSTANCE);
  }
}

View on GitHub (pinned to 12126d8942)