apache/iceberg · error · IllegalArgumentException

Cannot initialize AliyunClientFactory, missing no-arg constr

Error message

Cannot initialize AliyunClientFactory, missing no-arg constructor: %s

What it means

AliyunClientFactories.loadClientFactory resolves a custom AliyunClientFactory implementation class by name and requires a public no-arg constructor. If DynConstructors cannot find such a constructor (class missing, not public, or has required constructor args), it throws this IllegalArgumentException. This is a configuration/reflection error, not a runtime state error.

Source

Thrown at aliyun/src/main/java/org/apache/iceberg/aliyun/AliyunClientFactories.java:69

            AliyunProperties.CLIENT_FACTORY,
            DefaultAliyunClientFactory.class.getName());
    return loadClientFactory(factoryImpl, properties);
  }

  /**
   * Load an implemented {@link AliyunClientFactory} based on the class name, and initialize it.
   *
   * @param impl the class name.
   * @param properties to initialize the factory.
   * @return an initialized {@link AliyunClientFactory}.
   */
  private static AliyunClientFactory loadClientFactory(
      String impl, Map<String, String> properties) {
    DynConstructors.Ctor<AliyunClientFactory> ctor;
    try {
      ctor = DynConstructors.builder(AliyunClientFactory.class).hiddenImpl(impl).buildChecked();
    } catch (NoSuchMethodException e) {
      throw new IllegalArgumentException(
          String.format(
              "Cannot initialize AliyunClientFactory, missing no-arg constructor: %s", impl),
          e);
    }

    AliyunClientFactory factory;
    try {
      factory = ctor.newInstance();
    } catch (ClassCastException e) {
      throw new IllegalArgumentException(
          String.format(
              "Cannot initialize AliyunClientFactory, %s does not implement AliyunClientFactory.",
              impl),
          e);
    }

    factory.initialize(properties);
    return factory;

View on GitHub (pinned to 86d9c8fc54)

Solutions

Add a public no-arg constructor to your AliyunClientFactory implementation and read configuration from the passed properties map inside initialize().
Make sure the implementation class is public, top-level (or public static nested), and on the classpath.
Verify the fully-qualified class name configured in properties is spelled correctly.
If you cannot change the class, use the built-in AliyunClientFactoryImpl instead.

Example fix

// before
public class MyFactory implements AliyunClientFactory {
  public MyFactory(Map<String, String> props) { ... }
}

// after
public class MyFactory implements AliyunClientFactory {
  public MyFactory() {}

  @Override
  public void initialize(Map<String, String> props) { ... }
}

Defensive patterns

Strategy: validation

Validate before calling

Class<?> c = Class.forName(implClassName);
boolean ok = java.lang.reflect.Modifier.isPublic(c.getModifiers())
    && AliyunClientFactory.class.isAssignableFrom(c)
    && java.util.Arrays.stream(c.getConstructors())
        .anyMatch(k -> k.getParameterCount() == 0);

Prevention

Always give custom factories a public no-arg constructor and read config in initialize().
Keep factory classes public, static and top-level.
Validate the class name config with a unit test that loads it reflectively.

When it happens

Trigger: Setting the property that names the factory impl (e.g. via catalog properties key `io-impl`/Aliyun factory class config) to a class that has no public no-arg constructor, or a class name that does not exist (NoSuchMethodException from missing default ctor path).

Common situations: Users write a custom OSS client factory with a constructor taking properties; users typo the class name; the class is package-private or inner (non-static) so no accessible no-arg ctor exists; obfuscated/shaded jars rename the class.

Understand the failure class

Background: "is required", "must be set", "missing required field": configuration validation errors across open-source libraries — this error's family across 36 libraries.

Related errors

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/d397ada6b4c4d996. Report an issue: GitHub.