nginx cant find index alway returns 404 not found

Question

I am new to nginx and try to implement a webserver and access the index.php. If i try to visit the index.php nginx returns me an 404 Error.

This is my sites-enabled config :

server {
    listen 80;
    listen [::]:80;

    server_name  example.com www.example.com;
    root   /var/www/ilias;
    index  index.php;

    #access_log /var/log/nginx/example.com.access.log;
    #error_log /var/log/nginx/example.com.error.log;

    access_log /var/log/nginx/ilias.access.log;
    error_log /var/log/nginx/ilias.error.log;


    client_max_body_size 100M;

    autoindex off;

    location / {
    try_files $uri $uri/ /index.php?$query_string;
      }

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

I dont see a mistake, at least it should display me the index.php