管理页面显示空白

Created a PHP Website, Example.com and Login Page is example.com/admin

When I am filling the username and password details at example.com/admin.

Page Successfully loaded and showing successful redirecting to you but dashboard or admin panel showing blank screen.

check below error log

2019/05/04 02:21:52 [emerg] 16768#16768: unexpected end of file, expecting "}" in /etc/nginx/sites-enabled/default:92
2019/05/04 02:23:21 [notice] 16780#16780: signal process started

  thrown in /var/www/html/core/library/geoip.inc on line 572" while reading response header from upstream, client: 171.79.224.202, server: 157.230.229.11, request: "GET /admin/ HTTP/1.1", upstream: "fastcgi://unix:/var/run/php/php7.2-fpm.sock:", host: "157.230.229.11"
2019/05/04 03:23:16 [error] 30120#30120: *187 FastCGI sent in stderr: "PHP message: PHP Fatal error:  Uncaught Error: Call to undefined function mb_internal_encoding() in /var/www/html/core/library/geoip.inc:572
Stack trace:
#0 /var/www/html/core/library/geoip.inc(464): _geoip_seek_country(Object(GeoIP), 2874138826)
#1 /var/www/html/core/library/geoip.inc(503): geoip_country_id_by_addr(Object(GeoIP), '171.79.224.202')
#2 /var/www/html/admin/controllers/dashboard.php(106): geoip_country_name_by_addr(Object(GeoIP), '171.79.224.202')
#3 /var/www/html/admin/app.php(129): require('/var/www/html/a...')
#4 /var/www/html/admin/index.php(41): require('/var/www/html/a...')
#5 {main}
  thrown in /var/www/html/core/library/geoip.inc on line 572" while reading response header from upstream, client: 171.79.224.202, server: 157.230.229.11, request: "GET /admin/ HTTP/1.1", upstream: "fastcgi://unix:/var/run/php/php7.2-fpm.sock:", host: "157.230.229.11"

nginx/sites-available/default file is

server {
    listen 80 default_server;
    listen [::]:80 default_server;
    root /var/www/html;

    index index.php index.html index.htm index.nginx-debian.html;

    server_name 157.230.229.11;

    location / {
        #try_files $uri $uri/ =404;
    try_files $uri $uri/ /index.php?q=$uri&$args;
    }

    location ~ \.php$ {
        include snippets/fastcgi-php.conf;
        fastcgi_pass unix:/var/run/php/php7.2-fpm.sock;
    }

    location ~ /\.ht {
        deny all;
    }
}

also when I'm clicking any of page / sub-page showing homepage or if changed to it then is showing 404 not found nginx error but homepage works file.

Please Help me any one with this

Try this in your .htaccess file

RewriteEngine on
RewriteCond $1 !^(index\.php|public|\.txt)
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?$1