The web server won’t start: nginx or Apache

The site on your server has stopped opening, and systemctl restart doesn’t help. Work through the steps in order — the cause is usually found by the second or third.

1. Check the status

systemctl status nginx

For Apache, the service is apache2 on Ubuntu and Debian and httpd on AlmaLinux. The output includes the last lines of the log — often the error is already visible here. For more detail: journalctl -u nginx -n 50.

2. Test the configuration

sudo nginx -t                  # nginx
sudo apachectl configtest      # Apache

If an error crept in when you edited the settings, the command shows the file and line number. Fix it, test again and restart.

3. Look at the error log

The last lines: sudo tail -n 50 /var/log/nginx/error.log.

Common causes

• “Address already in use”. Port 80 or 443 is taken — often nginx and Apache are both trying to listen on it. Who is using the port and how to free it is covered in a separate article.
• Certificate or key not found. Check the paths in the settings and the permissions on the files.
• The disk is full. Check with df -h. Logs and old backups usually take up the most space.
• SELinux on AlmaLinux stops the web server reading the site’s files or connecting to an application — how to fix this.
• The server is running, but the site doesn’t open from outside. Check that the firewall allows ports 80 and 443, and that the domain points to the server’s IP address (domain lookup).