Bug 507282

Version: 6.4.3
Severity: Major / Critical (as it's a regression breaking core functionality)
Description:
Bluetooth audio output is completely broken for external speakers after updating KDE Plasma to version 6.4.3. This issue appears to be a regression and has been observed across different distributions that have received this specific Plasma version. Headphones connected via Bluetooth continue to work correctly.

Steps to Reproduce:
Ensure the system is updated to KDE Plasma 6.4.3 (observed on Fedora 42).

Power on and place a Bluetooth speaker (e.g., MAC address 00:02:3C:A3:44:21) into pairing mode.

Connect the Bluetooth speaker via KDE Plasma's Bluetooth settings (System Settings -> Bluetooth). The speaker shows as connected.

Attempt to play any audio (e.g., from a music player, browser, or system sounds).

Observed Results:
No sound is output from the connected Bluetooth speaker.

The speaker remains silent, even though it appears connected in system settings.

System logs (journalctl -f | grep -i "bluetooth\|pipewire") show the following relevant errors:

lip 20 10:35:19 ddzi-fedora bluetoothd[4586]: No matching connection for device
lip 20 10:35:20 ddzi-fedora bluetoothd[4586]: src/service.c:btd_service_connect() a2dp-source profile connect failed for 00:02:3C:A3:44:21: Device or resource busy
lip 20 10:35:20 ddzi-fedora bluetoothd[4586]: profiles/audio/avctp.c:avctp_control_confirm() Control: Refusing unexpected connect
lip 20 10:35:28 ddzi-fedora bluetoothd[4586]: /org/bluez/hci0/dev_00_02_3C_A3_44_21/sep2/fd1: fd(40) ready
lip 20 10:29:06 ddzi-fedora pipewire[1721]: pw.node: (bluez_output.00_02_3C_A3_44_21.1-102) running -> error
Specifically, the a2dp-source profile connect failed: Device or resource busy and Refusing unexpected connect messages indicate the speaker is rejecting the connection attempt, leading to the PipeWire node (bluez_output...) transitioning to an error state.

Attempting to switch the profile in System Settings -> Sound for the speaker shows that "A2DP Sink" is selected, but it doesn't resolve the issue.

Expected Results:
Audio should be played back correctly through the connected Bluetooth speaker when selected as the output device.

Additional Information:
This issue did not occur in previous versions of KDE Plasma (prior to 6.4.3).

Bluetooth headphones continue to function without issues, suggesting the problem is specific to how external Bluetooth speakers are handled.

Distro: Fedora 42

Bluetooth Controller: [If you know your Bluetooth adapter model, add it here, e.g., Intel AX200]

Audio Backend: PipeWire