Bug#963980: bumblebee-nvidia: Bumblebee daemon reported: error: [XORG] (EE) Unable to locate/open config directory

[Vincas Dargis]

I just this:

sudo apt purge --autoremove nvidia*
sudo apt install nvidia-driver bumblebee-nvidia primus-nvidia primus-vk-nvidia

And after reinstalling driver and all other bumbleblee-related packages, it 
started to work again.