oracle/graal · error · IllegalArgumentException

Invalid type:

Error message

Invalid type: 

What it means

Error "Invalid type: " thrown in oracle/graal.

Source

Thrown at espresso-compiler-stub/src/com.oracle.truffle.espresso.vmaccess/src/com/oracle/truffle/espresso/vmaccess/EspressoExternalVMAccess.java:918

    }

    EspressoExternalResolvedInstanceType getJavaLangObject() {
        return java_lang_Object;
    }

    EspressoExternalResolvedInstanceType[] getArrayInterfaces() {
        return arrayInterfaces;
    }

    JavaType lookupType(String name, EspressoExternalResolvedInstanceType accessingClass, boolean resolve) {
        JVMCIError.guarantee(!name.isEmpty(), "Name must not be empty");
        if (name.charAt(0) == '[') {
            int dims = 0;
            do {
                dims++;
            } while (dims < name.length() && name.charAt(dims) == '[');
            if (dims >= name.length()) {
                throw new IllegalArgumentException("Invalid type: " + name);
            }
            JavaType javaType = lookupNonArrayType(name.substring(dims), accessingClass, resolve);
            if (javaType instanceof EspressoResolvedJavaType resolved) {
                return new EspressoExternalResolvedArrayType(resolved, dims, this);
            }
            if (resolve) {
                throw new NoClassDefFoundError(name);
            }
            return UnresolvedJavaType.create(name);
        }
        return lookupNonArrayType(name, accessingClass, resolve);
    }

    private JavaType lookupNonArrayType(String name, EspressoExternalResolvedInstanceType accessingClass, boolean resolve) {
        assert !name.isEmpty() && name.charAt(0) != '[';
        if (name.length() == 1) {
            JavaKind kind = JavaKind.fromPrimitiveOrVoidTypeChar(name.charAt(0));
            return forPrimitiveKind(kind);

View on GitHub (pinned to a66e9ccd1d)

Solutions

1. Fix the condition reported by the error: Invalid type:
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: Invalid type:

When it happens

Trigger: Thrown at espresso-compiler-stub/src/com.oracle.truffle.espresso.vmaccess/src/com/oracle/truffle/espresso/vmaccess/EspressoExternalVMAccess.java:918 when the library encounters an invalid state.

Common situations: Occurs when a caller violates the contract guarded by this check: Invalid type:

AI-assisted analysis of oracle/graal@a66e9ccd1d (2026-08-14). Data as JSON: /api/errors/7fc9dd20e8607b57. Report an issue: GitHub.