gchq/CyberChef · error · OperationError

Encountered a non-implemented type: ${typeof object}

Error message

Encountered a non-implemented type: ${typeof object}

What it means

The top-level serialize() function handles null, primitives (via serializeBasicTypes), Arrays, and plain Objects. This 'should be unreachable' throw fires for any value that is not null, not a primitive, not an Array, and not a plain Object — e.g., a Symbol-wrapped object, a Map, a Set, or a class instance that is not caught by instanceof Object.

Source

Thrown at src/core/operations/PHPSerialize.mjs:119

                return `a:${object.length}:{${serializedElements.join("")}}`;
            } else if (object instanceof Object) {
                /**
                 * Objects
                 * Note: the output cannot be guaranteed to be in the same order as the input
                 */
                const serializedElements = [];
                const keys = Object.keys(object);

                for (const key of keys) {
                    serializedElements.push(`${serialize(key)}${serialize(object[key])}`);
                }

                return `a:${keys.length}:{${serializedElements.join("")}}`;
            }

            /** This should be unreachable */
            throw new OperationError(`Encountered a non-implemented type: ${typeof object}`);
        }

        return serialize(input);
    }
}

export default PHPSerialize;

View on GitHub (pinned to 4290ea7539)

Solutions

  1. Ensure the input is plain JSON-compatible data: only null, booleans, numbers, strings, arrays, and plain objects
  2. Convert Map/Set instances to plain objects or arrays before serializing
  3. Run JSON.parse(JSON.stringify(data)) to strip non-standard types before calling the operation

Example fix

// before
const data = { items: new Map([['a', 1]]) };
// after
const data = { items: Object.fromEntries(new Map([['a', 1]])) };
Defensive patterns

Strategy: type-guard

Validate before calling

// Pre-check: deep-validate that all values are JSON-safe
function isJsonSafe(v) {
  if (v === null) return true;
  const t = typeof v;
  if (t === 'boolean' || t === 'number' || t === 'string') return true;
  if (t !== 'object') return false;
  if (Array.isArray(v)) return v.every(isJsonSafe);
  if (Object.getPrototypeOf(v) !== Object.prototype) return false;
  return Object.values(v).every(isJsonSafe);
}

Type guard

function isPlainObject(v) {
  return v !== null && typeof v === 'object' &&
    (Object.getPrototypeOf(v) === Object.prototype || Object.getPrototypeOf(v) === null);
}

Try / catch

try {
  const result = chef.phpSerialize(input);
} catch (e) {
  if (/non-implemented type/i.test(e.message)) {
    console.error("Unsupported object type — sanitize input to plain JSON types");
  } else { throw e; }
}

Prevention

When it happens

Trigger: Input JSON contains values whose typeof is 'object' but that are not instances of Object or Array — e.g., a Map, Set, or a non-standard object created with Object.create(null). A Symbol or function value whose typeof is neither 'object' nor a handled primitive type.

Common situations: JSON.parse with a reviver that returns Map or Set instances. Programmatic invocation with data structures containing Symbol or function values. Data mutated after parsing to include non-JSON types.

Related errors

AI-assisted analysis of gchq/CyberChef@4290ea7539 (2026-08-13). Data as JSON: /api/errors/fa893a41d4625eaa. Report an issue: GitHub.