apache/druid · error · ProvisionException

Problem instantiating object at prefix[%s]: %s: %s.

Error message

Problem instantiating object at prefix[%s]: %s: %s.

What it means

JsonConfigurator.configurate() reflectively constructs the configured object (via a JSON-annotated constructor). If instantiation/invocation throws NoSuchMethodException, InstantiationException, IllegalAccessException, or InvocationTargetException, it is wrapped in this ProvisionException indicating the object at the given config prefix could not be constructed.

Source

Thrown at processing/src/main/java/org/apache/druid/guice/JsonConfigurator.java:151

        // using the JsonCreator annotated factory method or no-arg constructor.
        // We know it exists because verifyClazzIsConfigurable checks for it.
        Optional<Method> factoryMethod = findJsonCreatorFactoryMethod(defaultClass);
        if (factoryMethod.isPresent()) {
          config = (T) factoryMethod.get().invoke(null);
        } else {
          config = defaultClass.getConstructor().newInstance();
        }
      } else {
        config = jsonMapper.convertValue(jsonMap, clazz);
      }
    }
    catch (IllegalArgumentException e) {
      throw new ProvisionException(
          StringUtils.format("Problem parsing object at prefix[%s]: %s.", propertyPrefix, e.getMessage()), e
      );
    }
    catch (NoSuchMethodException | InstantiationException | IllegalAccessException | InvocationTargetException e) {
      throw new ProvisionException(
          StringUtils.format(
              "Problem instantiating object at prefix[%s]: %s: %s.",
              propertyPrefix,
              e.getClass().getSimpleName(),
              e.getMessage()
          ),
          e
      );
    }

    final Set<ConstraintViolation<T>> violations = validator.validate(config);
    if (!violations.isEmpty()) {
      List<String> messages = new ArrayList<>();

      for (ConstraintViolation<T> violation : violations) {
        StringBuilder path = new StringBuilder();
        try {
          Class<?> beanClazz = violation.getRootBeanClass();

View on GitHub (pinned to 9b90983fd2)

Solutions

1. Look at the wrapped cause (InvocationTargetException target) for the real constructor failure and fix that input
2. Verify the <x>.type value names a concrete, instantiable registered class
3. Ensure the extension providing the class is loaded and on the classpath
4. Check class constructor requirements (e.g. required args/annotations) after upgrades

Example fix

// before
-Ddruid.storage.type=org.apache.druid.storage.custom.MyStore  // abstract class
// after
-Ddruid.storage.type=org.apache.druid.storage.custom.MyStoreImpl

Class<?> clazz = jsonMapper.convertValue(map, Object.class).getClass();
// verify the configured type resolves to a concrete instantiable class
Assert.assertFalse(Modifier.isAbstract(clazz.getModifiers()));

try { startDruid(); } catch (ProvisionException e) {
  if (e.getMessage().startsWith("Problem instantiating object at prefix")) {
    log.error("Constructor failed for {}: {}", extractPrefix(e.getMessage()), e.getCause(), e);
  }
  throw e;
}

When it happens

Trigger: The configured class has no matching @JsonCreator constructor for the map, is abstract/interface, its constructor throws, or constructor access is restricted — all during Guice provider creation for a config-backed object.

Common situations: Configuring druid.<x>.type pointing to a class whose constructor throws due to invalid internal setup; pointing a config at an interface/abstract type; extension class present in loadList issues so its creator isn't visible; refactored class removing the old creator signature.

Related errors

• Failed to create K8s ApiClient instance
• Problem parsing object at prefix[%s]: %s.
• %s - %s
• Double dot in property: %s
• Dot at the end of property: %s

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/08d8071ddb2ab90f. Report an issue: GitHub.