quarkusio/quarkus · error · DefinitionException

Declaring more than one InterceptionProxy parameter is inval

Error message

Declaring more than one InterceptionProxy parameter is invalid: ${producerMethod}

What it means

A producer method may declare at most one InterceptionProxy parameter. ArC validates producer method parameters in Beans.createProducerMethod and throws this DefinitionException when a second parameter of type InterceptionProxy is encountered.

Source

Thrown at independent-projects/arc/processor/src/main/java/io/quarkus/arc/processor/Beans.java:201

                        "Ignoring producer method %s - declared as an @Alternative but not selected by @Priority or quarkus.arc.selected-alternatives",
                        declaringBean.getTarget().get().asClass().name() + "#" + producerMethod.name());
                return null;
            }
        }

        if (scope != null // `null` is just like `@Dependent`
                && !BuiltinScope.DEPENDENT.is(scope)
                && producerMethod.returnType().kind() == Kind.PARAMETERIZED_TYPE
                && Types.containsTypeVariable(producerMethod.returnType())) {
            throw new DefinitionException("Producer method return type is a parameterized type with a type variable, "
                    + "its scope must be @Dependent: " + producerMethod);
        }

        InterceptionProxyInfo interceptionProxy = null;
        for (MethodParameterInfo parameter : producerMethod.parameters()) {
            if (parameter.type().name().equals(DotNames.INTERCEPTION_PROXY)) {
                if (interceptionProxy != null) {
                    throw new DefinitionException(
                            "Declaring more than one InterceptionProxy parameter is invalid: " + producerMethod);
                }
                if (parameter.type().kind() != Kind.PARAMETERIZED_TYPE) {
                    throw new DefinitionException(
                            "InterceptionProxy parameter must be a parameterized type: " + producerMethod);
                }
                DotName targetClass = producerMethod.returnType().name();
                DotName bindingsSource = null;
                if (parameter.hasAnnotation(DotNames.BINDINGS_SOURCE)) {
                    Type bindingsSourceType = parameter.annotation(DotNames.BINDINGS_SOURCE).value().asClass();
                    if (bindingsSourceType.kind() != Kind.CLASS) {
                        throw new DefinitionException("@BindingsSource may only define a class type, got "
                                + bindingsSourceType.kind() + ": " + producerMethod);
                    }
                    bindingsSource = bindingsSourceType.name();
                }
                interceptionProxy = new InterceptionProxyInfo(targetClass, bindingsSource);
            }

View on GitHub (pinned to e1c734241f)

Solutions

Remove the duplicate InterceptionProxy parameter and use the single instance for all interceptions.
If different target types are needed, split into separate producer methods, each with one InterceptionProxy.

Example fix

// before
@Produces
Thing make(InterceptionProxy<Thing> p1, InterceptionProxy<Thing> p2) { ... }
// after
@Produces
Thing make(InterceptionProxy<Thing> proxy) {
  return proxy.create();
}

Defensive patterns

Strategy: validation

Validate before calling

long proxyParams = Arrays.stream(m.getParameterTypes())
        .filter(t -> t == InterceptionProxy.class).count();
if (proxyParams > 1) {
    throw new IllegalStateException("At most one InterceptionProxy parameter allowed: " + m);
}

Prevention

Declare exactly one InterceptionProxy parameter per producer
Use proxy.create(...) for each interception need from the single instance
Review producer signatures when merging refactors

When it happens

Trigger: A @Produces method declares two parameters whose type is io.quarkus.arc.InterceptionProxy; the loop over producerMethod.parameters() detects interceptionProxy already set.

Common situations: Copy-paste duplicating an InterceptionProxy parameter; misunderstanding InterceptionProxy as a repeatable helper type; refactoring merging two producer signatures.

Related errors

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/1e568e084ae06ee2. Report an issue: GitHub.