In the meantime I've done a re-install of ubuntu-gnome 17.04. After that nightlight is working as expected on my primary display.
I can chowever onfirm the report that nightlight does noth work on my secondary display, but I guess this is a separate bug. ** Bug watch added: GNOME Bug Tracker #783854 https://bugzilla.gnome.org/show_bug.cgi?id=783854 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1676131 Title: Gnome Night Light doesn't work To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-control-center/+bug/1676131/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
