I am trying to connect a thermal printer to a raspberry pi 4 running Raspbian GNU/Linux 12 (bookworm) using the Bluez API.
So far I managed to pair with the printer, but now I am struggling to connect the raspi with it. Since the printer uses a Bluetooth’s Serial Port Profile, I managed to connect with it via CLI with rfcomm, but I want to do it 100% programatically in a sort of wizard embedded in a django application.

I understood I first need to configure the profile, which I apparently did with:

import dbus
bus = dbus.SystemBus()
device_path = "/org/bluez/hci0/dev_xx_xx_xx_xx_xx_xx"

manager = dbus.Interface(bus.get_object("org.bluez", "/org/bluez"),
                        "org.bluez.ProfileManager1")


manager.RegisterProfile(device_path, "00001101-0000-1000-8000-00805f9b34fb", {})

When I try to connect to the printer via connect()I get the following error:

dbus.exceptions.DBusException: org.bluez.Error.NotAvailable: br-connection-profile-unavailable

I would really appretiate some help on that issue.