Method "Connect" with signature "" ... doesn't exist

[Matt-Hicks-Bose]

• bleak version: 0.7.0
• Python version: 3.7.3
• Operating System: Raspbian GNU/Linux 10 (buster)
• BlueZ version (bluetoothctl -v) in case of Linux: 5.50

Description

Trying to connect to a non-existent BLE device results in an exception. I am seeing this occur in my application code, but also with the examples get_services.py and service_explorer.py (by not changing the default MAC address in the examples).

What I Did

$ python3 service_explorer.py
Traceback (most recent call last):
  File "/home/pi/.local/lib/python3.7/site-packages/bleak/backends/bluezdbus/client.py", line 151, in connect
    ).asFuture(self.loop)
txdbus.error.RemoteError: org.freedesktop.DBus.Error.UnknownObject: Method "Connect" with signature "" on interface "org.bluez.Device1" doesn't exist


During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "service_explorer2.py", line 63, in <module>
    loop.run_until_complete(run(address, loop, True))
  File "/usr/lib/python3.7/asyncio/base_events.py", line 584, in run_until_complete
    return future.result()
  File "service_explorer2.py", line 29, in run
    async with BleakClient(address, loop=loop) as client:
  File "/home/pi/.local/lib/python3.7/site-packages/bleak/backends/client.py", line 49, in __aenter__
    await self.connect()
  File "/home/pi/.local/lib/python3.7/site-packages/bleak/backends/bluezdbus/client.py", line 154, in connect
    raise BleakError(str(e))
bleak.exc.BleakError: org.freedesktop.DBus.Error.UnknownObject: Method "Connect" with signature "" on interface "org.bluez.Device1" doesn't exist

[hbldh]

Trying to connect to a non-existent BLE device results in an exception.

Well, shouldn't it throw an exception? Maybe a better one though, e.g. a BleakError.

It generally means that the BlueZ deamon does not have a device with that address stored in its list of discovered devices. Run discover for longer or set timeout higher in the BleakClient.

[Matt-Hicks-Bose]

Thanks, that is a better error description and should reduce confusion.