oracle/graal · error · IllegalArgumentException

Unsupported annotation exception proxy: %s

Error message

Unsupported annotation exception proxy: %s

What it means

Error "Unsupported annotation exception proxy: %s" thrown in oracle/graal.

Source

Thrown at compiler/src/jdk.graal.compiler.vmaccess/src/jdk/graal/compiler/vmaccess/HostAnnotationValueConverter.java:324

    }

    /**
     * Converts one reflection annotation value, including JDK exception proxies, into the
     * representation used by {@link AnnotationValue}.
     */
    private static Object hostAnnotationMemberAsAnnotationValueElement(Annotation annotation, Method member, Object value, Function<Class<?>, ResolvedJavaType> classToType) {
        if (value instanceof TypeNotPresentExceptionProxy proxy) {
            return new MissingType(proxy.typeName(), proxy.getCause());
        }
        if (value instanceof DeferredAnnotationTypeMismatchExceptionProxy proxy) {
            return new ElementTypeMismatch(proxy.foundType);
        }
        if (value instanceof EnumConstantNotPresentExceptionProxy) {
            return invokeFailingAnnotationMember(annotation, member, classToType);
        }
        if (value instanceof ExceptionProxy) {
            if (!"sun.reflect.annotation.AnnotationTypeMismatchExceptionProxy".equals(value.getClass().getName())) {
                throw new IllegalArgumentException("Unsupported annotation exception proxy: " + value.getClass().getName());
            }
            return invokeFailingAnnotationMember(annotation, member, classToType);
        }
        if (value instanceof Enum<?> enumValue) {
            return new EnumElement(classToType.apply(enumValue.getDeclaringClass()), enumValue.name());
        }
        if (value instanceof Class<?> classValue) {
            return classToType.apply(classValue);
        }
        if (value instanceof Annotation annotationValue) {
            return toAnnotationValue(annotationValue, classToType);
        }
        Class<?> valueType = value.getClass();
        if (valueType.isArray()) {
            int length = Array.getLength(value);
            List<Object> elements = new ArrayList<>(length);
            for (int i = 0; i < length; i++) {
                elements.add(hostAnnotationMemberAsAnnotationValueElement(annotation, member, Array.get(value, i), classToType));

View on GitHub (pinned to a66e9ccd1d)

Solutions

1. Fix the condition reported by the error: Unsupported annotation exception proxy: {}
2. Check the throwing call site and ensure its documented preconditions (argument values, types, environment, or configuration) are satisfied before the call.

Example fix

Validate inputs and environment so that the failing condition does not occur: Unsupported annotation exception proxy: {}

When it happens

Trigger: Thrown at compiler/src/jdk.graal.compiler.vmaccess/src/jdk/graal/compiler/vmaccess/HostAnnotationValueConverter.java:324 when the library encounters an invalid state.

Common situations: Occurs when a caller violates the contract guarded by this check: Unsupported annotation exception proxy: {}

AI-assisted analysis of oracle/graal@a66e9ccd1d (2026-08-14). Data as JSON: /api/errors/a0275507c585be11. Report an issue: GitHub.