I couldn't runserver django on port 8000, in ubuntu:

terminal: python manage.py runserver Error: Error: That port is already in use.!!!!

I search which app closed the port 8000, after this command:

sudo netstat -ntlp

Also after installation htop, I tried to kill the causing app with killing its PID, but its impossible and don't work at all.

sudo apt-get install htop htop

this PID resist to killing with pid and any command name of app: app:gutenprint-pri pid: 3107 port:8000

finally I found that this app block my port 8000: gutenprint-pri thus I uninstall this app with app-center in ubuntu, and then port 8000 cleared