NGINX certificate issue : binding to port 80: Could not bind to IPv4 or IPv6

Question

I have an NGINX webserver and I'm using Certbot (letsencrypt) to renew my websites certificates. When I try to renew certificates I have this error :

binding to port 80: Could not bind to IPv4 or IPv6

So I checked what was using port 80 and I got this :

# lsof -Pnl +M -i6
COMMAND   PID     USER   FD   TYPE    DEVICE SIZE/OFF NODE NAME
nginx   17117        0    7u  IPv6 102365521      0t0  TCP *:443 (LISTEN)
nginx   17117        0    9u  IPv6 102365523      0t0  TCP *:80 (LISTEN)
nginx   17118       33    7u  IPv6 102365521      0t0  TCP *:443 (LISTEN)
nginx   17118       33    9u  IPv6 102365523      0t0  TCP *:80 (LISTEN)
nginx   17119       33    7u  IPv6 102365521      0t0  TCP *:443 (LISTEN)
nginx   17119       33    9u  IPv6 102365523      0t0  TCP *:80 (LISTEN)
sshd    18455        0    4u  IPv6  66436292      0t0  TCP *:22 (LISTEN)

It seems 3 different nginx are running am I right ?

I tried to stop nginx by running

/etc/init.d/nginx stop

I also tried like this

systemctl stop nginx

And when I check current process I still have 2 nginx running no matter if I run the above stop commands :

root     17117  0.0  0.1 161720  2284 ?        Ss   juin06   0:00 nginx: master process nginx -c /etc/nginx/nginx.conf
www-data 17118  0.0  0.3 161984  8208 ?        S    juin06   0:00 nginx: worker process
www-data 17119  0.0  0.3 161720  7484 ?        S    juin06   0:02 nginx: worker process

By the way I cannot start NGINX because I have got this error :

# systemctl start nginx
Job for nginx.service failed because the control process exited with error code.
See "systemctl status nginx.service" and "journalctl -xe" for details.

If someone can help me it would be nice :) !

Answer 1

For systemd to successfully manage (stop or restart) a service, it must have been started via systemd. If an nginx process has been started directly, systemctl will not recognize it and will try to start a second copy, or will be unable to stop the existing copy.

Do not use /etc/init.d or sudo nginx to start services – always use systemctl start nginx. Make sure your cronjobs or Certbot hooks do the same thing.