oracle/graal · error · IllegalStateException

object is not a static object

Error message

object {} is not a static object

What it means

JDWPContextImpl.getRefType(Object) expects its argument to be an Espresso StaticObject (the guest object representation) and returns its Klass; any other Java object is a caller bug, so it throws IllegalStateException. This is an internal debugger API contract, not a user-facing boundary.

Solutions

1. Pass only guest objects obtained from Espresso runtime APIs (StaticObject) to this method.
2. Add an instanceof StaticObject check before calling and skip/handle non-guest values.
3. Prefer the public JDWP/polyglot APIs instead of Espresso-internal classes.

Example fix

// before
KlassRef ref = jdwp.getRefType(maybeHostObject); // throws for host objects

// after
if (maybeHostObject instanceof StaticObject so) {
    KlassRef ref = jdwp.getRefType(so);
} else {
    // handle host-side value separately
}

boolean isGuestObject(Object o) { return o instanceof com.oracle.truffle.espresso.runtime.StaticObject; }

When it happens

Trigger: Calling getRefType with a host object, a boxed value, null-adjacent wrapper, or a polyglot Value's host receiver instead of the guest StaticObject; usually inside custom JDWP extensions or code that reached into Espresso internals.

Common situations: Tooling that reflects over Espresso runtime values and assumes raw java.lang.Object semantics; mixing host and guest object models in a debugger integration.

Related errors

• boxed object: is not a primitive
• Constant has unexpected type
• handshake failed - connection prematurely closed
• handshake failed - unrecognized message from the debugger
• handshake timeout

AI-assisted analysis of oracle/graal@a66e9ccd1d (2026-08-14). Data as JSON: /api/errors/91fb86ca842d9eb2. Report an issue: GitHub.

Appendix: source

Thrown at espresso/src/com.oracle.truffle.espresso/src/com/oracle/truffle/espresso/runtime/JDWPContextImpl.java:353

            return (String) UNCACHED.toDisplayString(staticObject, false);
        }
        return object.toString();
    }

    @Override
    public MethodVersionRef getMethodFromRootNode(RootNode root) {
        if (root instanceof EspressoRootNode) {
            return ((EspressoRootNode) root).getMethodVersion();
        }
        return null;
    }

    @Override
    public KlassRef getRefType(Object object) {
        if (object instanceof StaticObject) {
            return ((StaticObject) object).getKlass();
        } else {
            throw new IllegalStateException("object " + object + " is not a static object");
        }
    }

    @Override
    public KlassRef getReflectedType(Object classObject) {
        if (classObject instanceof StaticObject staticObject) {
            if (staticObject.getKlass().getType() == Types.java_lang_Class) {
                return (KlassRef) context.getMeta().java_lang_Class_0klass.getHiddenObject(staticObject);
            }
        }
        return null;
    }

    @Override
    public KlassRef[] getNestedTypes(KlassRef klass) {
        if (klass instanceof ObjectKlass objectKlass) {
            ArrayList<KlassRef> result = new ArrayList<>();
            List<Symbol<Name>> nestedTypeNames = objectKlass.getNestedTypeNames();

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