quarkusio/quarkus · error · DefinitionException

Multiple @Inject constructors found on

Error message

Multiple @Inject constructors found on 

What it means

A CDI bean class may declare at most one constructor annotated @Inject (the bean constructor). ArC counts @Inject-annotated constructors during bean processing and throws this DefinitionException (listing all of them) when a bean class has more than one.

Source

Thrown at independent-projects/arc/processor/src/main/java/io/quarkus/arc/processor/Injection.java:221

    private static void validateInjections(List<Injection> injections, BeanType beanType) {
        for (Injection injection : injections) {
            for (InjectionPointInfo ipi : injection.injectionPoints) {
                validateInjections(ipi, beanType);
            }
        }
    }

    static List<Injection> forBean(AnnotationTarget beanTarget, BeanInfo declaringBean, BeanDeployment beanDeployment,
            InjectionPointModifier transformer, BeanType beanType) {
        if (Kind.CLASS.equals(beanTarget.kind())) {
            List<Injection> injections = forClassBean(beanTarget.asClass(), beanTarget.asClass(), beanDeployment,
                    transformer, false, new HashSet<>());

            Set<AnnotationTarget> injectConstructors = injections.stream().filter(Injection::isConstructor)
                    .map(Injection::getTarget).collect(Collectors.toSet());
            if (injectConstructors.size() > 1) {
                throw new DefinitionException(
                        "Multiple @Inject constructors found on " + beanTarget.asClass().name() + ":\n"
                                + injectConstructors.stream().map(Object::toString).collect(Collectors.joining("\n")));
            }
            for (AnnotationTarget injectConstructor : injectConstructors) {
                Set<AnnotationInstance> parameterAnnotations = Annotations.getParameterAnnotations(beanDeployment,
                        injectConstructor.asMethod());
                for (AnnotationInstance annotation : parameterAnnotations) {
                    if (DotNames.DISPOSES.equals(annotation.name())) {
                        throw new DefinitionException(
                                "Bean constructor must not have a @Disposes parameter: " + injectConstructor);
                    }
                    if (DotNames.OBSERVES.equals(annotation.name())) {
                        throw new DefinitionException(
                                "Bean constructor must not have an @Observes parameter: " + injectConstructor);
                    }
                    if (DotNames.OBSERVES_ASYNC.equals(annotation.name())) {
                        throw new DefinitionException(
                                "Bean constructor must not have an @ObservesAsync parameter: " + injectConstructor);

View on GitHub (pinned to e1c734241f)

Solutions

1. Remove @Inject from all but one constructor; ArC will pick the single annotated one
2. If the class has exactly one constructor, remove @Inject entirely — it is used automatically
3. Make the no-arg constructor package-private or remove it if it was only there for frameworks

Example fix

// before
class MyBean { @Inject MyBean() {} @Inject MyBean(Other o) {} }
// after
class MyBean { @Inject MyBean(Other o) {} }

long n = java.util.Arrays.stream(MyBean.class.getDeclaredConstructors())
    .filter(c -> c.isAnnotationPresent(jakarta.inject.Inject.class)).count();
if (n > 1) throw new IllegalStateException("At most one @Inject constructor allowed on MyBean");

When it happens

Trigger: Annotating two or more constructors of a bean class with @Inject, e.g. after adding a new constructor with dependencies while leaving @Inject on the old no-arg constructor.

Common situations: Refactoring that adds a constructor for testing while keeping the old @Inject constructor; merge conflicts keeping duplicate constructors; not realizing only one constructor may carry @Inject.

Related errors

• No TCCL available
• Unsupported value:
• Unable to construct type for ${btRemovedBean}: ${e.getMessag
• Multiple disposed parameters found for ${disposerMethod}
• Invalid injection of Interceptor<T> bean, can only be used i

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/f8a7042ff487dea3. Report an issue: GitHub.