Why is BLE().config giving me a ValueError unknown config param?

[brianreinhold]

At the start of my application I have

        self.ble: BLE = BLE()
        self.ble.active(True)
        self.ble.config(bond=True)
        self.ble.config(io=Btle.IO_CAPABILITY_KEYBOARD_DISPLAY)
        self.ble.config(mitm=True)
        self.ble.config(le_secure=True)

Then later I have the following conditional just before making a connection

        if phd_info.service_uuids[0] == Btle.AndProprietaryWeightScale:
            print('LNI: Setting secure connections to False for proprietary A&D Scale')
            self.ble.config(le_secure=False)
            if self.ble.config('le_secure') == False:
                print('LNI: Successfully set secure connections to False')
        elif self.ble.config('le_secure') == False:
            print('LNI: ReSetting secure connections to True')
            self.ble.config(le_secure=True)

When the application is run, all those ble.config methods at the start not only give rise to no error but they appear to work.
However, when I dynamically set the secure connections to False ( a work around for a TI Bluetooth chip that chokes when it sees the secure connections flag set in a pairing request), the request to read back what I set gives
ValueError: unknown config param.
Note there is no error on setting the config. (Is there something missing in the documentation about reading back a config?) This is the sole example I could find in a test BDADDR=ble.config("mac") so it looks okay.

I do not understand that behavior. We are using the btstack on the PICO-W and have had to do a lot of work to support client-side pairing (Micropython does not support the pairing/bonding functionality with the btstack out of the box.) So far, our modifications seem to have worked with the various types of bonding procedures peripherals can throw at our client.

I am not sure these configs can be dynamically set but from the low-level documentation it certainly seems okay. In the pairing/bonding section there is this text

Before calling this, ensure that the io, mitm, le_secure, and bond configuration options are set via config

I do not see any implied restriction on when these fields can be set. They are also options in the aioble pairing method but in the case of a security request, the btstack handles it and aioble knows nothing about it. Thus the reason to clear the le_secure flag so the btstack sends a pairing request with that bit cleared.