Although I don’t know how much it helps you but couple of suggestions I got while searching for other bluetooth error:
- Downgrade bluez version, remove
/var/lib/bluetooth
folder and check - Try connecting using
bluetoothctl
instead of UI buttons, sometimes I too can’t connect properly using tray icon or UI setup - Try bluez-git instead of bluez
- make sure the Bluetooth speaker is in pairing mode and remove it from list and repair it in bluetoothctl: Can't connect my bluetooth headphones - #6 by joekamprad