Microsoft iot core raspberry pi - blood pressure

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Windows

Bluetooth

Raspberry-Pi

Dear Sirs,

​i'm trying to read ​characteristic Blood Pressure Measurement (0x2A35) of the service Blood Pressure (0x1810) but it give me the follow exception: There is no user session key for the specified logon session.

​Please check my code below, that error occurs when i do the follow command:

var t2 = await characteristic.WriteClientCharacteristicConfigurationDescriptorAsync(

GattClientCharacteristicConfigurationDescriptorValue.Indicate);



IReadOnlyList<gattcharacteristic> characteristicList;
characteristicList = gattService.GetCharacteristics(new Guid(UUID_CHARACTERISTIC_BLOOD_PRESSURE_MEASUREMENT));

if (characteristicList == null) return;
if (characteristicList.Count <= 0) return;

GattCharacteristic characteristic = characteristicList[0];

if (!characteristic.CharacteristicProperties.HasFlag(GattCharacteristicProperties.Indicate)) return;

characteristic.ProtectionLevel = GattProtectionLevel.Plain;

arrayCharacteristics[INDEX_BLOOD_PRESSURE] = characteristic;
characteristic.ValueChanged += bloodPressure_ValueChanged;

var t1 = await characteristic.ReadClientCharacteristicConfigurationDescriptorAsync();
var t2 = await characteristic.WriteClientCharacteristicConfigurationDescriptorAsync(GattClientCharacteristicConfigurationDescriptorValue.Indicate);
var t3 = await characteristic.ReadClientCharacteristicConfigurationDescriptorAsync();

What i'm doing wrong? What the message means?

Thank you a lot.​