nginx install: debian: Job for nginx.service failed because the control process exited with error code

 

>PROBLEM

Installing nginx:

apt install nginx

Returns:

  

Job for nginx.service failed because the control process exited with error code.
See "systemctl status nginx.service" and "journalctl -xe" for details.
invoke-rc.d: initscript nginx, action "start" failed.
● nginx.service - A high performance web server and a reverse proxy server
   Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since Sat 2020-09-26 22:49:18 UTC; 7ms ago
     Docs: man:nginx(8)
  Process: 21405 ExecStart=/usr/sbin/nginx -g daemon on; master_process on; (code=exited, status=1/FAILURE)
  Process: 21404 ExecStartPre=/usr/sbin/nginx -t -q -g daemon on; master_process on; (code=exited, status=0/SUCCESS)

Sep 26 22:49:17 mind4y.com nginx[21405]: nginx: [emerg] listen() to [::]:80, backlog 511 failed (98: Address already in use)
Sep 26 22:49:17 mind4y.com nginx[21405]: nginx: [emerg] listen() to 0.0.0.0:80, backlog 511 failed (98: Address already in use)
Sep 26 22:49:17 mind4y.com nginx[21405]: nginx: [emerg] listen() to [::]:80, backlog 511 failed (98: Address already in use)
Sep 26 22:49:18 mind4y.com nginx[21405]: nginx: [emerg] listen() to 0.0.0.0:80, backlog 511 failed (98: Address already in use)
Sep 26 22:49:18 mind4y.com nginx[21405]: nginx: [emerg] listen() to [::]:80, backlog 511 failed (98: Address already in use)
Sep 26 22:49:18 mind4y.com nginx[21405]: nginx: [emerg] still could not bind()
Sep 26 22:49:18 mind4y.com systemd[1]: nginx.service: Control process exited, code=exited status=1
Sep 26 22:49:18 mind4y.com systemd[1]: Failed to start A high performance web server and a reverse proxy server.
Sep 26 22:49:18 mind4y.com systemd[1]: nginx.service: Unit entered failed state.
Sep 26 22:49:18 mind4y.com systemd[1]: nginx.service: Failed with result 'exit-code'.
dpkg: error processing package nginx-full (--configure):
 subprocess installed post-installation script returned error exit status 1
dpkg: dependency problems prevent configuration of nginx:
 nginx depends on nginx-full (<< 1.10.3-1+deb9u4.1~) | nginx-light (<< 1.10.3-1+deb9u4.1~) | nginx-extras (<< 1.10.3-1+deb9u4.1~); however:
  Package nginx-full is not configured yet.
  Package nginx-light is not installed.
  Package nginx-extras is not installed.
 nginx depends on nginx-full (>= 1.10.3-1+deb9u4) | nginx-light (>= 1.10.3-1+deb9u4) | nginx-extras (>= 1.10.3-1+deb9u4); however:
  Package nginx-full is not configured yet.
  Package nginx-light is not installed.
  Package nginx-extras is not installed.

dpkg: error processing package nginx (--configure):
 dependency problems - leaving unconfigured
Errors were encountered while processing:
 nginx-full
 nginx
E: Sub-process /usr/bin/dpkg returned an error code (1)

>SOLUTION

The issue is caused by port collision. In this case Apache is already using port 80.

The tip is given by the log at line:

nginx[21405]: nginx: [emerg] listen() to 0.0.0.0:80

Switch Nginx or Apache to another port.
In this case, Nginx is switched to port 81.

1. Edit:

/etc/nginx/sites-enabled/default

Switch from:

server {
listen 80 default_server;
listen [::]:80 default_server;

To:

server {
listen 81 default_server;
listen [::]:81 default_server;

 

2. Start nginx

systemctl start nginx

3. Test:

nginx -t

>EXTRA

If desired to reinstall Nginx, uninstall first:

apt update

apt purge nginx
apt autoremove

- verifying dependencies:
apt -f install

>ENV

debian 9