quarkusio/quarkus · error · IllegalArgumentException

Unsupported annotation target

Error message

Unsupported annotation target

What it means

Generic build-time guard in the Qute ValueResolverGenerator: while generating a value resolver it encountered an annotation target kind it does not know how to process (not a method, field, or class accepted by the filter). This is effectively an internal unreachable-branch sentinel — the target kind at fault determines the failure, and it usually indicates an unsupported or malformed annotation placement on an endpoint or resolver candidate.

Source

Thrown at independent-projects/qute/generator/src/main/java/io/quarkus/qute/generator/ValueResolverGenerator.java:1019

        }
    }

    static boolean defaultFilter(AnnotationTarget target) {
        // Always ignore constructors, non-public members, synthetic and void methods
        switch (target.kind()) {
            case METHOD:
                MethodInfo method = target.asMethod();
                return Modifier.isPublic(method.flags())
                        && !isSynthetic(method.flags())
                        && method.returnType().kind() != org.jboss.jandex.Type.Kind.VOID
                        && !method.isConstructor()
                        && !method.isStaticInitializer();
            case FIELD:
                FieldInfo field = target.asField();
                return Modifier.isPublic(field.flags())
                        && !isSynthetic(field.flags());
            default:
                throw new IllegalArgumentException("Unsupported annotation target");
        }
    }

    public static boolean isSynthetic(int mod) {
        return (mod & 0x00001000) != 0;
    }

    public static boolean isGetterName(String name, Type returnType) {
        if (name.startsWith(GET_PREFIX)) {
            return true;
        }
        if (returnType == null
                || (returnType.name().equals(PrimitiveType.BOOLEAN.name()) || returnType.name().equals(DotNames.BOOLEAN))) {
            return name.startsWith(IS_PREFIX) || name.startsWith(HAS_PREFIX);
        }
        return false;
    }

View on GitHub (pinned to e1c734241f)

Solutions

1. Check the annotation placement on the reported element — it must be on a public method, field, or class
2. Avoid annotating constructors or synthetic members with Qute value-resolver annotations
3. Report as a Quarkus bug if the target looks legitimate

When it happens

Trigger: Thrown at independent-projects/qute/generator/src/main/java/io/quarkus/qute/generator/ValueResolverGenerator.java:1019 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/0f50fadb0be2c681. Report an issue: GitHub.