Night light brakes when screen dims

[Firen]

I'm using the night light function in Budgie which is set to a temperature of 4000 and the schedule is set from sunset to sunrise. When my display dims after X minutes of inactivity the night light function breaks which results in a much blue-er screen. When I move my mouse the dimming effect dissapears but and the temperature and brightness of my screen go back to the default value as if the night light function isn't on. Disabling and enabling the night light function fixes the issue until my screen dims again.

[Firen (f1ren)]

Sorry, I think I've created this bug on the wrong package (so the wrong place). But I have no idea where it should go. My apologies.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Thorsten Niehues (thorsten-niehues)]

I'm not sure if nightlight breaks after dim or after it turns off completely. (since it cannot dim any more after having lowest possible backlight already)

[Stéphane Guillou (stephane-guillou)]

I believe I have the same issue. I originally reported it as the current duplicate Bug #1791659.

The issue is as described here: the night light mode turns off as the screen starts dimming right before it blanks. The mode then needs to be turned off and on to work again.

If I have an external monitor connected, as "join monitors", the external monitor is the one that loses the night light, whereas the built-in display still has it. The workaround around this is unplugging and plugging the screen back in.

I use the following:

gnome-control-center version: 1:3.28.2-0ubuntu0.18.04.2
gnome-shell version: 3.28.3-0ubuntu0.18.04.2

System details:

OS: Ubuntu 18.04.1 LTS x86_64
Host: N230WU
Kernel: 4.15.0-33-lowlatency
Uptime: 3 days, 1 hour, 12 mins
Packages: 2921
Shell: bash 4.4.19
Resolution: 1920x1080, 1920x1080
DE: Budgie
WM: Mutter(Budgie)
Theme: Adwaita [GTK2/3]
Icons: Adwaita [GTK2/3]
Terminal: tilix
CPU: Intel i7-8550U (8) @ 4.000GHz
GPU: Intel UHD Graphics 620
Memory: 4168MiB / 15918MiB

[Stéphane Guillou (stephane-guillou)]

Just adding to my previous comment #4: the external monitor behaviour is inconsistent. With a different brand, the original workaround (turning night light off and back on) works, without needing to unplug the monitor.

[Sebastien Bacher (seb128)]

Testing on 18.10, the screen dimming doesn't impact the coloring. Do you use an external screen? Do you still see the issue?

[Stéphane Guillou (stephane-guillou)]

Okay I just did some more testing on only my built-in laptop display.
It is not the "dim screen when inactive" setting that breaks the night light, that works fine, the screen is dimmed at once, and the night light is still active.
What breaks the night light is the progressive dimming of the screen brightness that directly precedes the blanking of the screen when the "blank screen" setting is on (i.e. not set to "never").

When the night light is "broken" by the pre-blanking progressive dimming, it does not re-activate either when stopping the process by moving the mouse, nor when turning the display on again after the screen was blanked. To re-activate the night light, we have to go to the Night Light settings / widget and turn it off and on again.

Still on Ubuntu Budgie 18.04 derivative, with all packages up to date (bionic-security + bionic-updates).

Hopefully that makes it clearer, and @jesse111 can confirm.

[Sebastien Bacher (seb128)]

Testing on 18.10 the "progressive dimming before blanking" doesn't reset the color profile here. Could you trigger the bug and add the systemctl log from around the time the bug manifest itself?

[Stéphane Guillou (stephane-guillou)]

With `journalctl -r`, the only thing I get when the screen starts dimming and the nightlight is deactivated, is this line (username and machine name not shown):

Jan 20 22:42:02 xxxxx-xxxxx gnome-screensav[4274]: Source ID 1654 was not found when attempting to remove it

Hope this helps!

[Sebastien Bacher (seb128)]

hum, when you write "nightlight is deactivated" you mean it's on but get deactivated by the dimming? or is it off? would it be possible to get a debug log from gnome-settings-daemon (by editing the org.gnome.SettingsDaemon.Color.desktop Exec entry and adding --debug for example and then getting the journal log)?

[Launchpad Janitor (janitor)]

[Expired for gnome-control-center (Ubuntu) because there has been no activity for 60 days.]

[Stéphane Guillou (stephane-guillou)]

Hi Sebastien

I added `--debug` to the Exec line in org.gnome.SettingsDaemon.Color.desktop but now I get stuck on this when booting up:

started hold until boot process finishes up.

Could that be related? I can't think of anything else fancy I did, and now I can't use my computer :/

[Stéphane Guillou (stephane-guillou)]

Phew, thankfully every so often I was able to access the command line with Ctrl + Alt + F2 without it flashing back to the boot messages (maybe once every twenty times) and then removed the flag from the .desktop file. Took me a couple of hours as it was really erratic behaviour. (The recovery mode didn't help either, same flashing between bootup commands and black screen.)

I won't try that flag again! Any other way I can provide a useful log?