apache/beam · error · CannotProvideCoderException

Unable to find 'public static CoderProvider getCoderProvider

Error message

Unable to find 'public static CoderProvider getCoderProvider()' on %s

What it means

Thrown by DefaultCoder.coderFor when the class named in @DefaultCoder does not expose the required static method 'public static CoderProvider getCoderProvider()'. Beam uses reflection to obtain a CoderProvider from the annotated coder class; if the method is missing (NoSuchMethodException) it wraps the failure in CannotProvideCoderException.

Source

Thrown at sdks/java/core/src/main/java/org/apache/beam/sdk/coders/DefaultCoder.java:121

              String.format("Class %s does not have a @DefaultCoder annotation.", clazz.getName()));
        }

        @SuppressWarnings("rawtypes") // this is deliberate, as the user will pass FooCoder.class
        Class<? extends Coder> defaultAnnotationValue = defaultAnnotation.value();
        if (defaultAnnotationValue == null) {
          throw new CannotProvideCoderException(
              String.format(
                  "Class %s has a @DefaultCoder annotation with a null value.", clazz.getName()));
        }

        LOG.debug(
            "DefaultCoder annotation found for {} with value {}", clazz, defaultAnnotationValue);

        Method coderProviderMethod;
        try {
          coderProviderMethod = defaultAnnotationValue.getMethod("getCoderProvider");
        } catch (NoSuchMethodException e) {
          throw new CannotProvideCoderException(
              String.format(
                  "Unable to find 'public static CoderProvider getCoderProvider()' on %s",
                  defaultAnnotationValue),
              e);
        }

        CoderProvider coderProvider;
        try {
          coderProvider =
              Preconditions.checkStateNotNull(
                  (CoderProvider) coderProviderMethod.invoke(clazz /* ignored */));
        } catch (IllegalAccessException
            | IllegalArgumentException
            | InvocationTargetException
            | NullPointerException
            | ExceptionInInitializerError e) {
          throw new CannotProvideCoderException(
              String.format(

View on GitHub (pinned to 12126d8942)

Solutions

1. Add the static factory to the coder class: public static CoderProvider getCoderProvider() { return new FooCoderProvider(); }.
2. Use Beam's ProviderHelpers or an existing pattern (e.g. AvroCoder.getCoderProvider()) as a template.
3. Verify the method signature exactly matches: public static CoderProvider getCoderProvider(), no arguments.
4. As an alternative, register the coder via coderRegistry.registerCoderForClass(Foo.class, new FooCoder()) instead of relying on the annotation's reflective lookup.

Example fix

// before
public class EventCoder extends CustomCoder<Event> { ... }

// after
public class EventCoder extends CustomCoder<Event> {
  public static CoderProvider getCoderProvider() {
    return CoderProviders.fromStaticMethod(EventCoder.class, "getCoderProvider");
  }
}

try {
  MyCoder.class.getMethod("getCoderProvider");
} catch (NoSuchMethodException e) {
  throw new IllegalStateException("Coder class must define public static CoderProvider getCoderProvider()");
}

try {
  coder = registry.getCoder(TypeDescriptor.of(MyType.class));
} catch (CannotProvideCoderException e) {
  throw new IllegalStateException("Misconfigured @DefaultCoder target: " + e.getMessage(), e);
}

When it happens

Trigger: Annotating a class @DefaultCoder(FooCoder.class) where FooCoder defines no public static getCoderProvider() method returning CoderProvider; renaming or removing the method during refactoring.

Common situations: Hand-writing a custom coder and copying only the encode/decode methods without the provider factory; upgrading a coder library where the provider method was removed; typo like getCodersProvider().

Related errors

• Unable to invoke 'public static CoderProvider getCoderProvid
• cannot encode a null Byte
• cannot estimate size for unsupported null value
• NonDeterministicException(target, message, e)
• Unable to encode element '" + value + "' with coder '" + thi

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/b32f99a94aad0576. Report an issue: GitHub.