Cannot write characteristic with authentication on Windows 11

[XaviFernandezEspiga]

Hi all,

I have the following setup:
bleak version: 1.1.1
Python version: 3.13.7
Operating System: windows 11

and the following relevant code:

    async with BleakClient(device, timeout = 60) as client:
        if not client.is_connected:
            print("Unable to connect.")
            return

        print("Connected.")
		
        char = services.get_characteristic(uuid)
        if char and "write" in char.properties:
            timestamp = int(time.time())
            timestamp_bytes = struct.pack('<I', timestamp)
            try:
                    #client.pair()
	        await client.write_gatt_char(uuid, timestamp_bytes, response = True)
	except Exception as e:
		print(f"Error writing to {uuid}: {e}")	

I am unable to write to the characteristic of an external BLE client when authentication is needed. By the way, our device needs the client to pair using a keypass. I have tried to pair the device using Windows control panel and running the above code, but I get the error [WinError -2147023673] The user has cancelled the operation.

If instead I do not pair the device and directly run the code then I get the error Could not write value b'm\x87\xcdh' to characteristic 001C: Protocol Error 0x05: Insufficient Authentication, and no prompt is displayed by Windows so to introduce the passkey.

Finally, if I enable the code line client.pair(), I get another error, Could not pair with device: FAILED.

I would appreciate some help on this.

Thank you in advance

[dlech]

By the way, our device needs the client to pair using a keypass.

This would require some changes like #1100, but we've never managed to get that over the line to be included in Bleak yet. 😞

[XaviFernandezEspiga]

Understood, it is not possible then.