System settings is missing. I tried reinstall it as it mentioned here, but it seems to be installed and deactivated. This problem occurred when I installed Elementary desktop environment and uninstalled it afterwards.
I know this is already late but it can still help someone. This can happen when a library required to run gnome control center is missing, you can fix this by reinstalling or updating gnome. I was able to fix this on Debian 10 (buster) running GNOME desktop environment. Open terminal and run
sudo apt-get update
sudo apt-get install --reinstall task-gnome-desktop