Not booting after update, backlight:acpi_video0

I bought a brand new HP x360 435 g7 with ryzen 5 4500U with only FreeDOS pre-installed. I wanted to switch to linux, so I tried ubuntu, but nothing worked there. Since this is a new processor, I figured that manjaro would have newer drivers out of the box. It worked better, the only issue left is that the F4-F5 backlight buttons only manage to get the backlight between 50%-100% of intensity. I tried updating to a newer kernel, but during reboot I got this error message:

[FAILED] Failed to start Load/Save Screen Backlight ness of backlight:acpi_video0

I used timeshift to return to my old working kernel and it worked fine. But after updating my system yesterday, I again get stuck with the error message.

I did research and tried setting a Kernel Parameter:

GRUB_CMDLINE_LINUX_DEFAULT="quiet acpi_backlight=vendor"

But it doesn’t work, saying something like no vendor driver is specified

So back to timeshift, reset my kernel, more research. I tried this:

systemctl status systemd-backlight@backlight:acpi_video0.service

Output is:

● systemd-backlight@backlight:acpi_video0.service - Load/Save Screen Backlight Brightness of backlight:acpi_video0
     Loaded: loaded (/usr/lib/systemd/system/systemd-backlight@.service; static; vendor preset: disabled)
     Active: failed (Result: exit-code) since Mon 2020-08-17 11:26:39 CEST; 5min ago
       Docs: man:systemd-backlight@.service(8)
    Process: 1233 ExecStart=/usr/lib/systemd/systemd-backlight load backlight:acpi_video0 (code=exited, status=1/FAILURE)
   Main PID: 1233 (code=exited, status=1/FAILURE)

Aug 17 11:26:39 martin435g7 systemd[1]: Starting Load/Save Screen Backlight Brightness of backlight:acpi_video0...
Aug 17 11:26:39 martin435g7 systemd-backlight[1233]: Failed to get backlight or LED device 'backlight:acpi_video0': No such device
Aug 17 11:26:39 martin435g7 systemd[1]: systemd-backlight@backlight:acpi_video0.service: Main process exited, code=exited, status=1/FAILURE
Aug 17 11:26:39 martin435g7 systemd[1]: systemd-backlight@backlight:acpi_video0.service: Failed with result 'exit-code'.
Aug 17 11:26:39 martin435g7 systemd[1]: Failed to start Load/Save Screen Backlight Brightness of backlight:acpi_video0.
journalctl -b _PID=1233

output:

-- Logs begin at Mon 2020-08-17 11:26:36 CEST, end at Mon 2020-08-17 11:50:48 CEST. --
Aug 17 11:26:39 martin435g7 systemd-backlight[1233]: Failed to get backlight or LED device 'backlight:acpi_video0': No such device

Is there some way to get updates not crash my system AND getting my backlights to work…?
I am a complete newbie and definitely can’t figure this out on my own, I am grateful for every help I can get.

see this

Hi markur,

I have the same issue on a Asus G14 and while stephane’s answer may work and is a workaround I was able to continue booting by changing to another tty (Ctl+Alt+F2 or F3 etc) and then back to tty1 (my boot tty). It then boots into GDM as expected.

I might go for stephane’s suggestion myself as it I may get annoyed by this in the future. In fact since upgrading to kernel 5.8 I have 3 error messages similar to this.

Aha so that’s how you get into tty!! I kept reading about it but was too stupid to find out about ctrl+alt+F2, thanks.

So I updated again, including the unsafe kernel, then disabled the systemd backlight (like in stephanes post), then did a reboot, but got the error message again. Then I pressed ctrl alt f2 and disabled backlight again in tty2, then reboot, but then again error. Then I pressed ctrl alt f2, then ctrl alt f1 and it continued booting, nice.

After a few minutes on my desktop, my backlight turned dim and I realized that my keyboard buttons could now control my backlight from 10% - 100%, like it should.

I still get the error message all the time when booting, maybe I try switching off systemd backlight later, but I am just happy with being capable of updating and rebooting my system using ctrl alt f2 and ctrl alt f1.

Thanks for your help!