The error you’re seeing, GDBus.Error.org.bluez.Error.Failed: br-connection-unknown, is typically related to issues with the Bluetooth stack or the pairing process on the Raspberry Pi. Here’s a step-by-step troubleshooting guide to help resolve this issue:

1. Ensure Bluetooth is Enabled and Active

Make sure Bluetooth is enabled and the service is running:

sudo systemctl enable bluetooth
sudo systemctl start bluetooth

2. Update the System

Ensure that your Raspberry Pi is running the latest software and firmware:

sudo apt update
sudo apt full-upgrade
sudo reboot

3. Check Bluetooth Status

After reboot, check the Bluetooth service status:

systemctl status bluetooth

If it’s not running, there may be an issue with the installation or hardware.

4. Install Required Bluetooth Utilities

If you haven’t installed the necessary Bluetooth tools, you can do so by running:

sudo apt install pulseaudio pulseaudio-module-bluetooth pavucontrol bluez blueman

5. Restart Bluetooth Service

Restart the Bluetooth service:

sudo systemctl restart bluetooth

6. Check if the Device is Discoverable

Make sure that your Bluetooth device is discoverable by running:

bluetoothctl

In the Bluetooth control shell, use:

scan on
devices
pair <DEVICE_MAC_ADDRESS>
connect <DEVICE_MAC_ADDRESS>
trust <DEVICE_MAC_ADDRESS>

7. Ensure Correct Bluetooth Audio Configuration

In some cases, manually setting the audio sink may help. After successfully connecting to the device:

pactl list short sinks

Identify your Bluetooth device, then:

pacmd set-default-sink <SINK_NAME>

8. Test with Bluetooth Headphones or Speaker

If the connection fails with one device, try pairing with another Bluetooth audio device to ensure that the issue isn’t specific to the device you are trying to connect.

9. Check Logs for More Detailed Errors

If the issue persists, check the system logs for more details about the Bluetooth connection error:

journalctl -xe | grep bluetooth

10. Use Bluetooth Dongle (if applicable)

If you’re using an external Bluetooth dongle, it might cause a conflict. Try using a different dongle or ensure the correct drivers are installed.