CentOS7 Open Files – Fixing Too Many Open Files Issue on CentOS7

First time setting up a VPS – being mindful not to ask here unless I done due diligence and provide context.

On my remote VPS, through the terminal, almost all commands I run end up with an Error: Too many open files message and I need your help to move forward.

I run: CentOS Linux release 7.6.1810 (Core) on a machine with 1 CPU core and 2048Mb RAM. It has been setup with a LEMP stack Nginx 1.16.1, PHP-FPM 7.3.9, MariaDb 10.4.8 intended for a simple wordpress site.

I have tried:

1. Google and forum searches.
2. Applied these settings (manually restarting VPS manually via control panel each time):

System-wide settings in /etc/security/limits.conf:

nginx       soft    nofile      1024
nginx       hard    nofile      65536
root        hard    nofile      65536
root        soft    nofile      1024

adjustments to memory limits and uploads in /etc/php.ini:

memory_limit = 256M
file_uploads = On
upload_max_filesize = 128M
max_execution_time = 600
max_input_time = 600
max_input_vars = 3000

PHP rlimit settings in /etc/php-fpm.d/www.conf:

rlimit_files = 65535

Setting NGINX limits (and other settings) in nginx.conf:

user  nginx;
worker_processes  1;

error_log  /var/log/nginx/error.log warn;
pid        /var/run/nginx.pid;


events {
    worker_connections  10000;
}

worker_rlimit_nofile 100000;


http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  /var/log/nginx/access.log  main;

    sendfile        on;
    #tcp_nopush     on;

    keepalive_timeout  65;
    client_body_buffer_size 128k;
    client_header_buffer_size 10k;
    client_max_body_size 100m;
    large_client_header_buffers 4 256k;

    #gzip  on;

    include /etc/nginx/conf.d/*.conf;
    include /etc/nginx/sites-enabled/*.conf;
    server_names_hash_bucket_size 64;
}

Here is the output of cat /proc/sys/fs/file-nr:

45216   0   6520154

Here is the output of ps aux|grep nginx|grep -v grep:

root       928  0.0  0.0  46440  1192 ?        Ss   00:25   0:00 nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf
nginx      929  0.0  0.2  50880  6028 ?        S    00:25   0:00 nginx: worker process
nginx     9973  0.0  0.1 171576  4048 ?        S    04:28   0:00 php-fpm: pool www
nginx     9974  0.0  0.1 171576  4048 ?        S    04:28   0:00 php-fpm: pool www
nginx     9975  0.0  0.1 171576  4048 ?        S    04:28   0:00 php-fpm: pool www
nginx     9976  0.0  0.1 171576  4048 ?        S    04:28   0:00 php-fpm: pool www
nginx     9977  0.0  0.1 171576  4052 ?        S    04:28   0:00 php-fpm: pool www

Switching user to nginx with su - nginx and checking limits with:
ulimit -Sn returns 1024
ulimit -Hnreturns 65536

The lsof | wc -l command returns: 4776

Hope you can help steer me in the right direction to solve the Too Many Files problem!

EDIT
– the following command shows more info:

service nginx restart

Redirecting to /bin/systemctl restart nginx.service
Error: Too many open files
Job for nginx.service failed because a configured resource limit was exceeded. See "systemctl status nginx.service" and "journalctl -xe" for details.
[root@pars ~]# systemctl status nginx.service
● nginx.service - nginx - high performance web server
   Loaded: loaded (/usr/lib/systemd/system/nginx.service; enabled; vendor preset: disabled)
  Drop-In: /usr/lib/systemd/system/nginx.service.d
           └─worker_files_limit.conf
   Active: failed (Result: resources) since Fri 2019-09-13 05:32:23 CEST; 14s ago
     Docs: http://nginx.org/en/docs/
  Process: 1113 ExecStop=/bin/kill -s TERM $MAINPID (code=exited, status=0/SUCCESS)
  Process: 1125 ExecStart=/usr/sbin/nginx -c /etc/nginx/nginx.conf (code=exited, status=0/SUCCESS)
 Main PID: 870 (code=exited, status=0/SUCCESS)
   CGroup: /system.slice/virtualizor.service/system.slice/nginx.service

Sep 13 05:32:22 pars.work systemd[1]: Starting nginx - high performance web server...
Sep 13 05:32:22 pars.work systemd[1]: PID file /var/run/nginx.pid not readable (yet?) after start.
Sep 13 05:32:22 pars.work systemd[1]: Failed to set a watch for nginx.service's PID file /var/run/nginx.pid: Too many open files
Sep 13 05:32:23 pars.work systemd[1]: Failed to kill control group: Input/output error
Sep 13 05:32:23 pars.work systemd[1]: Failed to kill control group: Input/output error
Sep 13 05:32:23 pars.work systemd[1]: Failed to start nginx - high performance web server.
Sep 13 05:32:23 pars.work systemd[1]: Unit nginx.service entered failed state.
Sep 13 05:32:23 pars.work systemd[1]: nginx.service failed.