<coreBluetooth>peripheralとしてアドバタイズするために実装したが、エラーが出てしまい進みません。

<coreBluetooth>peripheralとしてアドバタイズする

swift、coreBluetoothともに初心者です。
coreBluetoothの理解のために、まずperipheralでサービスUUIDを指定してそれをcentralで検索するというシステムを作っています。
色々調べながら作成してcentralの方は完成したのですが、peripheralの方でエラーが出てしまい、詰まってしまっています。
central、peripheralはそれぞれ別のプロジェクトで作成して、2端末で実験しています。

発生している問題・エラーメッセージ

*** Terminating app due to uncaught exception 'Invalid Object', reason: 'Object <CBMutableService: xxxx Primary = YES, UUID = xxxx, Included Services = (null), Characteristics = (
    "<CBMutableCharacteristic: xxxx UUID = xxxx, Value = (null), Properties = xxxx, Permissions = xxxx, Descriptors = (null), SubscribedCentrals = (\n)>"
)> is invalid'
*** First throw call stack:
(xxxx)
libc++abi: terminating with uncaught exception of type NSException
*** Terminating app due to uncaught exception 'Invalid Object', reason: 'Object <CBMutableService: xxxx Primary = YES, UUID = xxxx, Included Services = (null), Characteristics = (
    "<CBMutableCharacteristic: xxxx UUID = xxxx, Value = (null), Properties = xxxx, Permissions = xxxx, Descriptors = (null), SubscribedCentrals = (\n)>"
)> is invalid'
terminating with uncaught exception of type NSException

該当のソースコード

class ViewController: UIViewController, CBPeripheralManagerDelegate{
    var manager: CBPeripheralManager!
    var service: CBMutableService!
    var characteristic: CBMutableCharacteristic!
    override func viewDidLoad() {
        super.viewDidLoad()
    
        self.manager = CBPeripheralManager(delegate : self, queue : nil, options: nil)
    }
   
    func peripheralManagerDidUpdateState(_ peripheral: CBPeripheralManager) {
        switch peripheral.state {
        case .poweredOn:
            service = CBMutableService(type: CBUUID(string: "xxxx"), primary: true)
            let properties: CBCharacteristicProperties = [.notify, .read, .write]
            let permissions: CBAttributePermissions = [.readable, .writeable]

            characteristic = CBMutableCharacteristic(type: CBUUID(string: "xxxx"),properties: properties, value: nil, permissions: permissions)
            
            self.service.characteristics = [self.characteristic]
            self.manager.add(self.service)
        case .unknown:
            print("bluetooth error")
        case .resetting:
            print("bluetooth error")
        case .unsupported:
            print("bluetooth error")
        case .unauthorized:
            print("bluetooth error")
        case .poweredOff:
            print("bluetooth error")
        @unknown default:
            print("bluetooth error")
        }
    }

    func peripheralManager(_ peripheral: CBPeripheralManager, didAdd service: CBService, error: Error?) {
        if error != nil {
            print("Service Add Failed...")
            return
        }
        print("Service Add Success!")

        if (self.manager.isAdvertising == false) {
            //アドバタイズ開始
            print("start")
            manager.startAdvertising([CBAdvertisementDataServiceUUIDsKey: [service], CBAdvertisementDataLocalNameKey: "TestPeripheralDevice"])
        }
    }

 
    func peripheralManagerDidStartAdvertising(_ peripheral: CBPeripheralManager, error: Error?) {
        if let error = error {
            print("Failed... error: (error)")
            return
        }
        print("Succeeded!")
    }