Night Light not working in Ubuntu 20.04

Question

Today I realized that Night Light stopped working in my machine. When I try to set it up, nothing happens. See attached gif:

I am not sure what's causing it to fail. I don't know if there are any logs generated by this tool, or if there's another way to enable Night Light.

Any idea what to try? This was working a few months ago.

When I check /var/log/syslog, there are some messages related to night light when I use the «Sunset to Sunrise» schedule, but nothing indicates that it failed:

Sep 19 22:46:37 sambayon gnome-control-c[22940]: no sunset data, using 16.00
Sep 19 22:46:37 sambayon gnome-control-c[22940]: no sunrise data, using 8.00

Solution 1

I encountered the same problem in 20.04, so I tried to reinstall gnome-control-center and then tried to restart my computer and it works.

Try running this command in a terminal to reinstall control center:

sudo apt-get install --reinstall gnome-control-center

and then restart you computer.

Solution 2

For me, It worked by just rebooting my system.

Comments

[Admin]

As a workaround, I have installed the sct program and using it manually, but it would be nice if I could fix Night Light.

[Admin]

I just realized that the night light wouldn't show up in a OBS recorded video. Regardless of that, there's no noticeable change in the display color temperature. What happens in the gif, is the same as what I'm seeing on the screen.

[Admin]

It happened to me too. I have it set to manual timing, from 05:00 to 04:59. When it broke, even the nightlight icon did not show up in the panel. But I noticed that my monitors (laptop + external HDMI) have disappeared from the Settings app's Color settings sidebar item. I set the preinstalled D50 color profile for my laptop's screen on that Color settings UI. But now only my printer had shown up to set a color profile to: the monitors did not. I think it's related. A reboot however restored everything: the Color settings UI, the laptop screen color profile, and night light.

[Admin]

@Levente - you should post this as an answer as it seems to be a solution, and also so it can be voted upon.

[Admin]

Not only you, and not only 20.04. I just come to notice that night light is out here too! Ubuntu 21.10.

[Francesco Borzi]

Reinstallation of gnome-control-center is not possible, it cannot be downloaded. for me just restarting my PC solved the problem.

[Admin]

Why you don't uninstall/disable F.lux instead?