Can't open serial port - UWP

I am trying to convert my WPF app to UWP app. My app uses the Serial Port class to communicate with a device. After I switched to UWP the same code that opens the connection to the device, using the Serial Port class, stopped working.

public MotorControl(string portName, Settings settings)
{
    this.settings = settings;
    this.serialPort = new SerialPort(portName, 9600)
    {
        DtrEnable = true,
        RtsEnable = true
    };
    this.serialPort.ErrorReceived += Port_ErrorReceived;
    this.serialPort.DataReceived += Port_DataReceived;
}
public void Connect()
{
    this.serialPort.Open();
    Thread.Sleep(this.settings.delayBetweenConnectAntWifi);
    this.SetNetworkMode("wifi");
}

When I am trying to open the connection I am getting this error:

System.IO.IOException
  HResult=0x80070000
  Message=The operation completed successfully
  Source=System.IO.Ports
  StackTrace:
   at System.IO.Ports.InternalResources.WinIOError(Int32 errorCode, String str)
   at System.IO.Ports.SerialStream..ctor(String portName, Int32 baudRate, Parity parity, Int32 dataBits, StopBits stopBits, Int32 readTimeout, Int32 writeTimeout, Handshake handshake, Boolean dtrEnable, Boolean rtsEnable, Boolean discardNull, Byte parityReplace)

I tried to use Serial Device

public MotorControl(string portName, Settings settings)
{
    this.settings = settings;
    this.portName = portName;
}

private async Task SetupSerialDevice()
{
    string aqs = SerialDevice.GetDeviceSelector(this.portName);
    var myDevices = await DeviceInformation.FindAllAsync(aqs, null);
    if (myDevices.Count == 0)
    {
        return;
    }
    this.serialDevice = await SerialDevice.FromIdAsync(myDevices.First().Id);
    this.serialDevice.BaudRate = 9600;
    this.serialDevice.DataBits = 8;
    this.serialDevice.StopBits = SerialStopBitCount.One;
    this.serialDevice.Parity = SerialParity.None;
    this.serialDevice.Handshake = SerialHandshake.None;
    this.serialDevice.ReadTimeout = TimeSpan.FromMilliseconds(1000);
    this.serialDevice.WriteTimeout = TimeSpan.FromMilliseconds(1000);
    this.dataWriter= new DataWriter(this.serialDevice.OutputStream);
    this.dataReader= new DataReader(this.serialDevice.InputStream);
    this.readPortThread = new Thread(this.ReadPort);
    this.readPortThread.Start();
}
public async void Connect()
{
    await this.SetupSerialDevice();
    Thread.Sleep(this.settings.delayBetweenConnectAntWifi);
     this.SetNetworkMode("wifi");
}

But, SerialDevice.FromIdAsync keeps returning null.

<Package
  xmlns="http://schemas.microsoft.com/appx/manifest/foundation/windows10"
  xmlns:mp="http://schemas.microsoft.com/appx/2014/phone/manifest"
  xmlns:uap="http://schemas.microsoft.com/appx/manifest/uap/windows10"
  xmlns:genTemplate="http://schemas.microsoft.com/appx/developer/windowsTemplateStudio"
  xmlns:iot="http://schemas.microsoft.com/appx/manifest/iot/windows10"
  xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities"
  IgnorableNamespaces="uap mp genTemplate iot rescap">
.
.
.
<Capabilities>
    <rescap:Capability Name="confirmAppClose"/>
    <Capability Name="internetClient" />
    <iot:Capability Name="lowLevelDevices"/>
    <DeviceCapability Name="serialCommunication">
      <Device Id="any">
        <Function Type="name:serialPort" />
      </Device>
    </DeviceCapability>
  </Capabilities>

The problem was that before I tried to connect to the device I used this function to find all ports:

public async static Task<ObservableCollection<string>> GetPortNames()
{
    string aqs = SerialDevice.GetDeviceSelector();
    var deviceCollection = await DeviceInformation.FindAllAsync(aqs);
    ObservableCollection<string> portNamesList = new ObservableCollection<string>();
    foreach (var item in deviceCollection)
    {
       SerialDevice serialDevice = await SerialDevice.FromIdAsync(item.Id);
       string portName = serialDevice.PortName;
       portNamesList.Add(portName);
    }
    return portNamesList;
}

and i didn't do a serialDevice.Dispose(); at the end of the foreach.

After adding serialDevice.Dispose(); I was able to use the good old SerialPort.