oracle/graal · error · IllegalArgumentException

expected an EspressoExternalObjectConstant got {}

Error message

expected an EspressoExternalObjectConstant got {}

What it means

Error "expected an EspressoExternalObjectConstant got {}" thrown in oracle/graal.

Source

Thrown at espresso-compiler-stub/src/com.oracle.truffle.espresso.vmaccess/src/com/oracle/truffle/espresso/vmaccess/EspressoExternalMetaAccessProvider.java:184

        } else {
            fields = declaringType.getInstanceFields(false);
        }
        EspressoResolvedJavaType type = lookupJavaType(reflectionField.getType());
        for (ResolvedJavaField field : fields) {
            if (field.getName().equals(name) && field.getType().equals(type)) {
                return field;
            }
        }
        throw new NoSuchFieldError(reflectionField.toString());
    }

    @Override
    public ResolvedJavaType lookupJavaType(JavaConstant constant) {
        if (constant.isNull() || constant.getJavaKind().isPrimitive()) {
            return null;
        }
        if (!(constant instanceof EspressoExternalObjectConstant objectConstant)) {
            throw new IllegalArgumentException("expected an EspressoExternalObjectConstant got " + safeGetClass(constant));
        }
        return objectConstant.getType();
    }

    @Override
    public Signature parseMethodDescriptor(String methodDescriptor) {
        return new EspressoExternalSignature(access, methodDescriptor);
    }

    @Override
    public long getMemorySize(JavaConstant constant) {
        throw JVMCIError.unimplemented();
    }

    @Override
    public JavaConstant encodeDeoptActionAndReason(DeoptimizationAction action, DeoptimizationReason reason, int debugId) {
        throw JVMCIError.unimplemented();
    }

View on GitHub (pinned to a66e9ccd1d)

Solutions

1. Fix the condition reported by the error: expected an EspressoExternalObjectConstant got {}
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: expected an EspressoExternalObjectConstant got {}

When it happens

Trigger: Thrown at espresso-compiler-stub/src/com.oracle.truffle.espresso.vmaccess/src/com/oracle/truffle/espresso/vmaccess/EspressoExternalMetaAccessProvider.java:184 when the library encounters an invalid state.

Common situations: Occurs when a caller violates the contract guarded by this check: expected an EspressoExternalObjectConstant got {}

AI-assisted analysis of oracle/graal@a66e9ccd1d (2026-08-14). Data as JSON: /api/errors/970d92f290ddf304. Report an issue: GitHub.