I don't think the GUI is meant to start bluetoothd at all. It only toggles the power state of the Bluetooth hardware. It assumes bluetoothd is always running. So failure to restart after a crash is a problem with bluez's systemd scripting.
** Package changed: gnome-control-center (Ubuntu) => bluez (Ubuntu) -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to bluez in Ubuntu. https://bugs.launchpad.net/bugs/1948990 Title: Bluetooth does not turn on via gnome-control-center after bluetooth.service crash Status in bluez package in Ubuntu: Fix Released Bug description: I had bluetooth crash (see logs below). After the crash, I attempted to restart bluetooth by pressing the On/Off switch in the top-right of the Bluetooth tab of gnome-control-center (it was set to off). After pressing the switch, the switch read "On", but the display of Bluetooth devices still appeared as it does when Bluetooth is off (it read "Bluetooth Turned Off\nTurn on to connect devices and receive file transfers."). I was able to remedy the situation by manually executing `sudo bluetoothd`. I did this while the above On/Off switch was "Off" and the Bluetooth device list said Bluetooth was off. After executing, the Bluetooth device list listed all my Bluetooth devices as expected. This is with bluetoothd 5.48. Bluetooth crash logs ``` 12:22:15 pulseaudio: (6856.168| 0.576) [pulseaudio] bluez5-util.c: Bluetooth daemon disappeared 12:22:15 systemd: bluetooth.service: Failed with result 'core-dump'. 12:22:15 systemd: bluetooth.service: Failed with result 'core-dump'. 12:22:15 systemd: bluetooth.service: Main process exited, code=dumped, status=11/SEGV 12:22:15 kernel: bluetoothd[816]: segfault at 31 ip 0000562f7fa9bea2 sp 00007ffd0d54b720 error 4 in bluetoothd[562f7fa00000+f3000] 10:28:31 kernel: hid-generic 0005:046D:B019.0007: input,hidraw6: BLUETOOTH HID v0.06 Keyboard [MX Master 2S] on F4:D1:08:9E:7B:85 10:28:31 bluetoothd: bt_uhid_send: Invalid argument (22) 10:28:31 bluetoothd: bt_uhid_send: Invalid argument (22) 10:28:31 bluetoothd: bt_uhid_send: Invalid argument (22) 10:28:31 bluetoothd: bt_uhid_send: Invalid argument (22) 10:28:31 bluetoothd: bt_uhid_send: Invalid argument (22) 10:28:31 bluetoothd: bt_uhid_send: Invalid argument (22) 10:28:31 bluetoothd: bt_uhid_send: Invalid argument (22) 10:28:31 bluetoothd: bt_uhid_send: Invalid argument (22) 10:28:31 bluetoothd: bt_uhid_send: Invalid argument (22) 10:28:31 bluetoothd: bt_uhid_send: Invalid argument (22) ``` ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: gnome-control-center 1:3.28.2-0ubuntu0.18.04.6 Uname: Linux 5.10.0-051000-generic x86_64 ApportVersion: 2.20.9-0ubuntu7.26 Architecture: amd64 CurrentDesktop: ubuntu:GNOME Date: Wed Oct 27 13:00:09 2021 InstallationDate: Installed on 2021-01-04 (295 days ago) InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426) SourcePackage: gnome-control-center UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/bluez/+bug/1948990/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp