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Marco
Asked: 2020-09-20 21:43:30 +0800 CST

Night Light not working in Ubuntu 20.04

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

trying to enable night light

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
system-settings 20.04 night-light

7 Answers

  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.

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  2. For me, It worked by just rebooting my system.

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  3. For NVIDIA GPU users: I had to reinstall my NVIDIA drivers after a kernel update. You can check if your driver is working with nvidia-smi -- if not, you may need to install drivers.

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  4. I encountered the same issue in Ubuntu 20.10. After turning on night light, I restart the computer and it works normally.

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  5. Flux was conflicting with the night light program, enabling the Manual mode worked for me.

    enter image description here

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  6. Try disabling MST in your Monitor's OSD if it has that option.

    Multi Stream Transport allows daisy-chaining multiple monitors via display port. I have a multiple-monitor setup and recognized that on the one monitor that has this option night light wasn't working at all.

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  7. A simple reboot seems to correct this fluke occurance as pointed out by Levente, above in comments to the original post.

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

    IN SHORT, REBOOT HIT THE NAIL ON THE HEAD OVER HERE.

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