Bluetooth adapter not detected on Linux

Question

I've been using Arch Linux for a while and bluetooth has been working without issues. Now, for no explicable reason, Arch doesn't detect my bluetooth adapters anymore.

I tried doing:
$ sudo systemctl enable bluetooth,
$ sudo systemctl start bluetooth and
$ sudo systemctl start dbus.

I've enabled generic bluetooth drivers:
$ sudo modprobe btusb.

I've installed: bluez, bluez-utils-compat and blueman.

$ sudo lsmod | grep bluetooth returns:

bluetooth             634880  11 btrtl,btintel,bnep,btbcm,btusb
ecdh_generic           24576  1 bluetooth
rfkill                 28672  7 bluetooth,acer_wmi,cfg80211
crc16                  16384  2 bluetooth,ext4

$ sudo lspci | grep blue returns nothing.

$ sudo hciconfig returns nothing.

$ sudo hcitool dev returns:

Devices:

$ sudo dmesg | grep Blue returns:

[  283.807549] Bluetooth: Core ver 2.22
[  283.807585] Bluetooth: HCI device and connection manager initialized
[  283.807588] Bluetooth: HCI socket layer initialized
[  283.807589] Bluetooth: L2CAP socket layer initialized
[  283.807594] Bluetooth: SCO socket layer initialized
[  349.781130] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[  349.781135] Bluetooth: BNEP filters: protocol multicast
[  349.781148] Bluetooth: BNEP socket layer initialized

$ sudo rfkill list returns:

0: acer-wireless: Wireless LAN
    Soft blocked: no
    Hard blocked: no
1: acer-bluetooth: Bluetooth
    Soft blocked: no
    Hard blocked: no
2: phy0: Wireless LAN
    Soft blocked: no
    Hard blocked: no

I've done:

$ bluetoothctl
[bluetoothctl]# scan on
No default controller available

When I open blueman-adapters, it opens but the window doesn't have any contents:

And when I open blueman-manager, the only functioning buttons are the View and Help menus:

Some important info (if needed):

Model:           Acer Aspire S13 S5-371
Network Card:    Qualcomm Atheros QCA61x4A
uname -r:        4.15.14-1-ARCH
BIOS Ver:        v1.5
OSes:            Windows 10, Arch Linux (dual boot using rEFInd)
Built in Bluetooth 4.0 support

Answer 1

Same symptoms as in the question happend to me on a Dell XPS 13 after installing Wacom software for a Intuos BT S tablet.

Solution for me was disabling Bluetooth in the BIOS, rebooting and enabling it in the BIOS again, as is said in this thread: https://ubuntuforums.org/showthread.php?t=2348005

Answer 2

No need to speculate as I've already solved this issue.

I went into Windows and found out that bluetooth didn't work there either (there was no slider to turn bluetooth on or off).

However, I figured out that if I opened the action menu (WIN-KEY+A) then clicked on the bluetooth icon twice (which was blue and had my phone's name on it, weird), bluetooth started working again somehow. I went back to Linux and it was working there as well. Problem solved it seems.

Answer 3

Whilst this is not an answer, I provide it here in the hope that it could be useful for people landing in this thread. Here you go:

I had troubles with my Philips SHB9850NC and I resolved the issue by installing pulseaudio-module-bluetooth. Later I've installed blueman too, which is a Gnome thing. Since I use KDE, I've removed blueman after that. Then troubles started to happen: my Bluetooth adapter vanished from existence.

The procedure below is intended to reinstall the entire Bluetooth stack for KDE, including pulseaudio-module-bluetooth. However, this didn't solve the issue. My Bluetooth adapter is still not detected.

$ sudo apt install --reinstall -y bluetooth bluez bluez-firmware bluez-hcidump bluez-cups bluez-tools pulseaudio-module-bluetooth
$ for cmd in unload load ;do sudo pactl ${cmd}-module module-bluetooth-discover ;done
$ for cmd in force-reload restart ;do sudo service bluetooth ${cmd} ;done