Hey,

I'm developing an app that connects ta a BLE beacon, for this I use the BluetoothLEAdvertisementWatcher API. When I receive an advertisement I want to connect to the device to read the GATT characteristics.

So I start a BLEwatcher

        BluetoothLEAdvertisementWatcher watcher;
        watcher.Received  = OnAdvertisementReceived;
        watcher.Stopped  = OnAdvertisementWatcherStopped;
        watcher.Start();

Then I try to access the device

    private async void OnAdvertisementReceived(BluetoothLEAdvertisementWatcher watcher, BluetoothLEAdvertisementReceivedEventArgs eventArgs)
    {
        var address = eventArgs.BluetoothAddress;

        BluetoothLEDevice device = await BluetoothLEDevice.FromBluetoothAddressAsync(eventArgs.BluetoothAddress);
        Debug.WriteLine(device.Name   " - "   device.DeviceId);
        ....

This fails with (at FromBluetoothAddressAsync line)

An exception of type 'System.IO.FileNotFoundException' occurred in mscorlib.ni.dll but was not handled in user code

Additional information: The system cannot find the file specified. (Exception from HRESULT: 0x80070002)    

The funny thing is: if I open the system's bluetooth devices window it works fine!

So when I open the bluetooth devices window and run the app the error is not thrown, when I close the bluetooth devices window it throws the error.

Anyone know a solution?

Apparently it does work on build 10.0.10586.218; /u/MkeyAllison & /u/jenmsft maybe this is something to add to the current build bugs list?

I found this online from someone with the same issue:

LUMIA 950, Windows 10, 1511, 10.0.14332.1001

Exception thrown on FromIdAsync(): 'System.IO.FileNotFoundException' in mscorlib.ni.dll

LUMIA 730, Windows 10, 1511, 10.0.10586.218

Exception thrown on FindAllAsync(): 'System.ArgumentException'

LUMIA 920, Windows 10, 1511, 10.0.10586.218

No Error!