Kernel Bluetooth errors every second after full system update

Issues & Assistance
1

After ‘pacman -Syu’ today, 2026-June-20, I’m getting a stream of Bluetooth errors in journalctl every second. My last full system update was 2026-June-16 and that boot had none of these errors.

Jun 20 14:11:31 serrano kernel: Bluetooth: hci0: HCI Enhanced Setup Synchronous Connection command is advertised, but not supported.
Jun 20 14:11:31 serrano kernel: Bluetooth: hci0: Failed to set up firmware (-2)
Jun 20 14:11:31 serrano kernel: Bluetooth: hci0: Failed to load firmware file (-2)
Jun 20 14:11:31 serrano kernel: bluetooth hci0: Direct firmware load for mediatek/mt7927/BT_RAM_CODE_MT6639_2_1_hdr.bin failed with error -2

I’m running KDE Plasma and in System Settings > Bluetooth the panel is quickly flashing between “No Bluetooth adapters found” and “No devices paired” and the Enabled slider flashes visible and not in both the left-hand menu Bluetooth option and the panel itself.

I disabled and stopped ‘bluetooth.service’ but that didn’t stop the errors.

In previous boots, I got no errors like this. I only see ‘dbus-broker-launch[1003]: Activation request for ‘org.bluez’ failed.’

I don’t know how to proceed.

2

Looking into it more since the error line is from the kernel messing with bluetooth.service won’t help.

Likely cause is the new 7.1.1-2-cachyos kernel has references for the “mediatek/mt7927/BT_RAM_CODE_MT6639_2_1_hdr.bin” file but it doesn’t exist in linux-firmware-mediatek or even upstream in the repo


~ ❯ ls -la /usr/lib/firmware/mediatek/mt7927/
total 1852
drwxr-xr-x 1 root root     138 Jun  5 20:59 ./
drwxr-xr-x 1 root root    2808 Jun  5 20:59 ../
-rw-r--r-- 1 root root  297142 May 23 05:28 WIFI_MT6639_PATCH_MCU_2_1_hdr.bin.zst
-rw-r--r-- 1 root root 1596646 May 23 05:28 WIFI_RAM_CODE_MT6639_2_1.bin.zst

A suggestion was to extract BT_RAM_CODE_MT6639_2_1_hdr.bin from a Windows driver package for my motherboard, or wait until the linux-firmware-mediatek package gets the file which is apparently in under review

I worry about manually putting a file in place that could later conflict with an official package update.

3

I was able to download the MTK version of the Win11 Bluetooth driver from my motherboard manufacturer website, and use the extract_firmware.py script from the AUR repo to get the BT_RAM_CODE_MT6639_2_1_hdr.bin file.

Claude says the next step is

sudo cp BT_RAM_CODE_MT6639_2_1_hdr.bin /usr/lib/firmware/mediatek/mt7927/
sudo mkinitcpio -P

Is sudo mkinitcpio -P correct for CachyOS?

4

Are you using Limine?
If yes, I believe it is:
sudo limine-update

I think I have the same issue, where the latest kernel is causing a 70sec boot delay due to the missing bluetooth.

5

I dont know about anything else here but, yes, Cachy does use mkinitcpio.

6

Instead of going the mkinitcpio route I tried the modprobe route and it seemed OK.

sudo cp BT_RAM_CODE_MT6639_2_1_hdr.bin /usr/lib/firmware/mediatek/mt7927/
sudo modprobe -r btusb btmtk   # unload the modules
sudo modprobe btusb            # reload; btmtk pulls in automatically

Since it looked OK, I did a full shutdown and power on, and with this new boot the errors are gone.

Now I will need to keep a close eye on the linux-firmware-mediatek package so I can remove this temporary workaround when the package contains the needed file.

Edit: I have not tested that the Bluetooth adapter is actually working, just that it stopped the 4 errors every 1 second in journalctl.