quarkusio/quarkus · error · DeploymentException

Can only inject AsyncResponse on methods marked @Suspended o

Error message

Can only inject AsyncResponse on methods marked @Suspended on 

What it means

Build-time validation error in EndpointIndexer: an endpoint method declares a parameter of type AsyncResponse but is not annotated with @Suspended, which RESTEasy Reactive requires to enable suspended async handling. The method/class context is appended to the message.

Source

Thrown at independent-projects/resteasy-reactive/common/processor/src/main/java/org/jboss/resteasy/reactive/common/processor/EndpointIndexer.java:1536

                        currentMethodInfo);
            }
        }

        if (!typeHandled) {
            elementType = toClassName(paramType, currentClassInfo, actualEndpointInfo, index);
            addReaderForType(additionalReaders, paramType);

            if (type != ParameterType.CONTEXT && type != ParameterType.BEAN && type != ParameterType.BODY
                    && type != ParameterType.ASYNC_RESPONSE && type != ParameterType.MULTI_PART_FORM) {
                handleOtherParam(existingConverters, errorLocation, hasRuntimeConverters, builder, elementType,
                        currentMethodInfo);
            }
            if (type == ParameterType.CONTEXT && elementType.equals(SseEventSink.class.getName())) {
                builder.setSse(true);
            }
        }
        if (suspendedAnnotation != null && !elementType.equals(AsyncResponse.class.getName())) {
            throw new DeploymentException(
                    "Can only inject AsyncResponse on methods marked @Suspended on " + builder.getErrorLocation());
        }
        if (builder.isSingle() && builder.getSeparator() != null) {
            throw new DeploymentException(
                    "Single parameters should not be marked with @Separator on " + builder.getErrorLocation());
        }
        builder.setElementType(elementType);
        return builder;
    }

    private boolean isFormParamConvertible(Type paramType) {
        // let's not call the array converter for byte[] for multipart
        if (paramType.kind() == Kind.ARRAY
                && paramType.asArrayType().constituent().kind() == Kind.PRIMITIVE
                && paramType.asArrayType().constituent().asPrimitiveType().primitive() == Primitive.BYTE) {
            return false;
        } else {
            return true;

View on GitHub (pinned to e1c734241f)

Solutions

1. Annotate the AsyncResponse parameter with @Suspended
2. Or use Uni/CompletionStage return types for async endpoints instead

When it happens

Trigger: Thrown at independent-projects/resteasy-reactive/common/processor/src/main/java/org/jboss/resteasy/reactive/common/processor/EndpointIndexer.java:1536 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/0c46fd422072258d. Report an issue: GitHub.