Can not restart Nginx, "Job for nginx.service failed because the control process exited with error code." [duplicate]

I have a digitalocean droplet with Ubuntu 16.04 running on it. I am serving mostly static sites from it with Nginx, but it suddenly stopped working.

(As you might understand from this intro, I am quite the beginner at all of this.)

I've tried to restart nginx:

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

systemctl status nginx.service:

$ systemctl status nginx.service
● 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 2019-04-25 12:31:46 UTC; 55s ago
     Docs: man:nginx(8)
  Process: 8232 ExecStart=/usr/sbin/nginx -g daemon on; master_process on; (code=exited, status=1/FAILURE)
  Process: 8221 ExecStartPre=/usr/sbin/nginx -t -q -g daemon on; master_process on; (code=exited, status=0/SUCCESS)

journalctl -xe

    $ sudo journalctl -u nginx
    - Logs begin at Thu 2019-03-21 01:07:26 UTC, end at Thu 2019-04-25 12:54:26 UTC. --
Apr 25 10:33:29 ubuntu-s-michaelsimsoe systemd[1]: Stopping A high performance web server and a reverse proxy server...
Apr 25 10:33:29 ubuntu-s-michaelsimsoe systemd[1]: Stopped A high performance web server and a reverse proxy server.
-- Reboot --
Apr 25 10:34:16 ubuntu-s-michaelsimsoe systemd[1]: Starting A high performance web server and a reverse proxy server...
Apr 25 10:34:17 ubuntu-s-michaelsimsoe nginx[1242]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Apr 25 10:34:17 ubuntu-s-michaelsimsoe nginx[1242]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Apr 25 10:34:18 ubuntu-s-michaelsimsoe nginx[1242]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Apr 25 10:34:18 ubuntu-s-michaelsimsoe nginx[1242]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Apr 25 10:34:18 ubuntu-s-michaelsimsoe nginx[1242]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Apr 25 10:34:18 ubuntu-s-michaelsimsoe nginx[1242]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Apr 25 10:34:19 ubuntu-s-michaelsimsoe nginx[1242]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Apr 25 10:34:19 ubuntu-s-michaelsimsoe nginx[1242]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Apr 25 10:34:19 ubuntu-s-michaelsimsoe nginx[1242]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Apr 25 10:34:19 ubuntu-s-michaelsimsoe nginx[1242]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Apr 25 10:34:20 ubuntu-s-michaelsimsoe nginx[1242]: nginx: [emerg] still could not bind()
Apr 25 10:34:20 ubuntu-s-michaelsimsoe systemd[1]: nginx.service: Control process exited, code=exited status=1
Apr 25 10:34:20 ubuntu-s-michaelsimsoe systemd[1]: nginx.service: Failed with result 'exit-code'.
Apr 25 10:34:20 ubuntu-s-michaelsimsoe systemd[1]: Failed to start A high performance web server and a reverse proxy server.
Apr 25 12:08:48 ubuntu-s-michaelsimsoe systemd[1]: Starting A high performance web server and a reverse proxy server...
Apr 25 12:08:48 ubuntu-s-michaelsimsoe nginx[21464]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Apr 25 12:08:48 ubuntu-s-michaelsimsoe nginx[21464]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Apr 25 12:08:49 ubuntu-s-michaelsimsoe nginx[21464]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Apr 25 12:08:49 ubuntu-s-michaelsimsoe nginx[21464]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Apr 25 12:08:49 ubuntu-s-michaelsimsoe nginx[21464]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Apr 25 12:08:49 ubuntu-s-michaelsimsoe nginx[21464]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Apr 25 12:08:50 ubuntu-s-michaelsimsoe nginx[21464]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Apr 25 12:08:50 ubuntu-s-michaelsimsoe nginx[21464]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Apr 25 12:08:50 ubuntu-s-michaelsimsoe nginx[21464]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Apr 25 12:08:50 ubuntu-s-michaelsimsoe nginx[21464]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Apr 25 12:08:51 ubuntu-s-michaelsimsoe nginx[21464]: nginx: [emerg] still could not bind()
Apr 25 12:08:51 ubuntu-s-michaelsimsoe systemd[1]: nginx.service: Control process exited, code=exited status=1
Apr 25 12:08:51 ubuntu-s-michaelsimsoe systemd[1]: nginx.service: Failed with result 'exit-code'.
Apr 25 12:08:51 ubuntu-s-michaelsimsoe systemd[1]: Failed to start A high performance web server and a reverse proxy server.
Apr 25 12:10:24 ubuntu-s-michaelsimsoe systemd[1]: Starting A high performance web server and a reverse proxy server...
Apr 25 12:10:25 ubuntu-s-michaelsimsoe nginx[25175]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Apr 25 12:10:25 ubuntu-s-michaelsimsoe nginx[25175]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Apr 25 12:10:25 ubuntu-s-michaelsimsoe nginx[25175]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Apr 25 12:10:25 ubuntu-s-michaelsimsoe nginx[25175]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Apr 25 12:10:26 ubuntu-s-michaelsimsoe nginx[25175]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Apr 25 12:10:26 ubuntu-s-michaelsimsoe nginx[25175]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Apr 25 12:10:26 ubuntu-s-michaelsimsoe nginx[25175]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Apr 25 12:10:26 ubuntu-s-michaelsimsoe nginx[25175]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Apr 25 12:10:27 ubuntu-s-michaelsimsoe nginx[25175]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Apr 25 12:10:27 ubuntu-s-michaelsimsoe nginx[25175]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Apr 25 12:10:27 ubuntu-s-michaelsimsoe nginx[25175]: nginx: [emerg] still could not bind()
Apr 25 12:10:27 ubuntu-s-michaelsimsoe systemd[1]: nginx.service: Control process exited, code=exited status=1
Apr 25 12:10:27 ubuntu-s-michaelsimsoe systemd[1]: nginx.service: Failed with result 'exit-code'.
Apr 25 12:10:27 ubuntu-s-michaelsimsoe systemd[1]: Failed to start A high performance web server and a reverse proxy server.
Apr 25 12:12:59 ubuntu-s-michaelsimsoe systemd[1]: Starting A high performance web server and a reverse proxy server...
Apr 25 12:12:59 ubuntu-s-michaelsimsoe nginx[30965]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Apr 25 12:12:59 ubuntu-s-michaelsimsoe nginx[30965]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Apr 25 12:12:59 ubuntu-s-michaelsimsoe nginx[30965]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Apr 25 12:12:59 ubuntu-s-michaelsimsoe nginx[30965]: nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
Apr 25 12:13:00 ubuntu-s-michaelsimsoe nginx[30965]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)

The following have been done by me before I noticed the errors: * Changed root password * Changed password for user michaels * Changed ownership of website folders (I'm trying to set up webhooks)

Any thoughts on what it might be?

EDIT: some additional information

$ sudo nginx -t
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful

$ ps -A | nginx
nginx: [alert] could not open error log file: open() "/var/log/nginx/error.log" failed (13: Permission denied)
2019/04/25 13:09:32 [warn] 28351#28351: the "user" directive makes sense only if the master process runs with super-user privileges, ignored in /etc/nginx/nginx.conf:1
2019/04/25 13:09:32 [emerg] 28351#28351: BIO_new_file("/etc/letsencrypt/live/huske.michaelsimsoe.no/fullchain.pem") failed (SSL: error:0200100D:system library:fopen:Permission denied:fopen('/etc/letsencrypt/live/huske.michaelsimsoe.no/fullchain.pem','r') error:2006D002:BIO routines:BIO_new_file:system lib)

Before I installed nginx I had som pages served by Apache. I can reach these still.

Solution 1:

Some other process is already running and bound to ports 80/443, thus systemd cannot start nginx. This is almost always because the process was started manually instead of via systemd, or because you tried to start two different web servers at the same time.

To resolve the problem, kill the process yourself before restarting it via systemd.

sudo killall apache2