xbacklight not working in ubuntu 16.10

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

is there a workaround ? Because actually i cant set the brightness of my Notebook in i3-wm.

Also looking for a workaround if anyone has any suggestions?

As a workaround you could write a different value in /sys/class/backlight/intel_backlight/brightness. Requires root.

xbacklight output: No outputs have backlight property

Some sort of workaround:

1) add udev rule /etc/udev/rules.d/90-backlight.rules:
ACTION=="add", SUBSYSTEM=="backlight", RUN+="/bin/chgrp video /sys/class/backlight/%k/brightness"
ACTION=="add", SUBSYSTEM=="backlight", RUN+="/bin/chmod g+w /sys/class/backlight/%k/brightness"

2) add yourself to group video: sudo usermod -a -G video $USER

3) run: sudo udevadm control -R && sudo udevadm trigger -c add -s backlight

I am using this script as a workaround for my keyboard buttons: https://github.com/Skraelingjar/bright but it's not perfect.

I also came across https://github.com/snobb/xbright

It is still not working for me in 17.04

You can use xfce4-power-manager it is working for me, plus you can have additional benefits like notification on battery low and few more things.

$ sudo apt install xfce4-power-manager

You can add automatically start on boot at ~/.config/i3/conf
exec xfce4-power-manager

Just use light instead...
Otherwise it is a mess to fix it, especially if you have intel and nvidia graphics together!
Checkout->https://github.com/haikarainen/light

Experiencing this issue on a Dell Vostro 3300 with Ubuntu 16.04.3 (I know the OP has reported it on 16.10)

xbacklight stopped working just now after an 'apt updgrade'. Ubuntu 16.04.3, Dell XPS-13.
Writing directly to /sys/class/backlight/intel_backlight/brightness still works.

In my case this turned out to be a known bug with the "modesetting" graphics driver, a fix for which would be available in linux 4.11 earliest:
https://bugs.freedesktop.org/show_bug.cgi?id=96572
Perhaps xbacklight works out-of-the-box on Ubuntu 17.10 :)

Googling around suggests Ubuntu 16.04 switched to modesetting driver recently (but I could not find definitive info on this).

Switching back to the intel driver fixed the issue for me: I edited the file
/usr/share/X11/xorg.conf.d/10-intel-modesetting.conf
to load the "intel" driver instead of "modesetting" driver.