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 Thu 2017-08-10 03:47:22 EDT; 13ms ago
  Process: 18996 ExecStart=/usr/sbin/nginx -g daemon on; master_process on; (code=exited, status=1/FAILURE)
  Process: 18995 ExecStartPre=/usr/sbin/nginx -t -q -g daemon on; master_process on; (code=exited, status=0/SUCCESS)

Aug 10 03:47:21 ip50 nginx[18996]: nginx: [emerg] listen() to [::]:80, backlog 511 failed (98: Address already in use)
Aug 10 03:47:21 ip50 nginx[18996]: nginx: [emerg] listen() to 0.0.0.0:80, backlog 511 failed (98: Address already in use)
Aug 10 03:47:21 ip50 nginx[18996]: nginx: [emerg] listen() to [::]:80, backlog 511 failed (98: Address already in use)
Aug 10 03:47:22 ip50 nginx[18996]: nginx: [emerg] listen() to 0.0.0.0:80, backlog 511 failed (98: Address already in use)
Aug 10 03:47:22 ip50 nginx[18996]: nginx: [emerg] listen() to [::]:80, backlog 511 failed (98: Address already in use)
Aug 10 03:47:22 ip50 nginx[18996]: nginx: [emerg] still could not bind()
Aug 10 03:47:22 ip50 systemd[1]: nginx.service: Control process exited, code=exited status=1
Aug 10 03:47:22 ip50 systemd[1]: Failed to start A high performance web server and a reverse proxy server.
Aug 10 03:47:22 ip50 systemd[1]: nginx.service: Unit entered failed state.
Aug 10 03:47:22 ip50 systemd[1]: nginx.service: Failed with result 'exit-code'.
dpkg: error processing package nginx-core (--configure):
 subprocess installed post-installation script returned error exit status 1
dpkg: dependency problems prevent configuration of nginx:
 nginx depends on nginx-core (>= 1.10.3-0ubuntu0.16.04.2) | nginx-full (>= 1.10.3-0ubuntu0.16.04.2) | nginx-light (>= 1.10.3-0ubuntu0.16.04.2) | nginx-extras (>= 1.10.3-0ubuntu0.16.04.2); however:
  Package nginx-core is not configured yet.
  Package nginx-full is not installed.
  Package nginx-light is not installed.
  Package nginx-extras is not installed.
 nginx depends on nginx-core (<< 1.10.3-0ubuntu0.16.04.2.1~) | nginx-full (<< 1.10.3-0ubuntu0.16.04.2.1~) | nginx-light (<< 1.10.3-0ubuntu0.16.04.2.1~) | nginx-extras (<< 1.10.3-0ubuntu0.16.04.2.1~); however:
  Package nginx-core is not configured yet.
  Package nginx-full is not installed.
  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-core
 nginx
E: Sub-process /usr/bin/dpkg returned an error code (1)