...upstream sent too big header while reading response header from upstream...

fastcgi_buffers 8 16k; # increase the buffer size for PHP-FTP
fastcgi_buffer_size 32k; # increase the buffer size for PHP-FTP
fastcgi_connect_timeout 60;
fastcgi_send_timeout 300;
fastcgi_read_timeout 300;

server {
    listen 80;
    server_name pm.use.ge;
    root /var/www/pm.use.ge/public_html;

    add_header X-Frame-Options "SAMEORIGIN";
    add_header X-XSS-Protection "1; mode=block";
    add_header X-Content-Type-Options "nosniff";

    index index.html index.htm index.php;

    charset utf-8;

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

    location = /favicon.ico { access_log off; log_not_found off; }
    location = /robots.txt  { access_log off; log_not_found off; }

    error_page 404 /index.php;

    location ~ \.php$ {
        fastcgi_pass unix:/var/run/php/php7.4-fpm.sock;
        fastcgi_index index.php;
        fastcgi_param SCRIPT_FILENAME $realpath_root$fastcgi_script_name;

        include fastcgi_params;                                                                                                                                >        deny all;
    }
}

server {
    listen 80;
    server_name pm.use.ge;
    root /var/www/pm.use.ge/public_html;

    add_header X-Frame-Options "SAMEORIGIN";
    add_header X-XSS-Protection "1; mode=block";
    add_header X-Content-Type-Options "nosniff";

    index index.html index.htm index.php;

    charset utf-8;

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

    location = /favicon.ico { access_log off; log_not_found off; }
    location = /robots.txt  { access_log off; log_not_found off; }

    error_page 404 /index.php;

    location ~ \.php$ {
        fastcgi_pass unix:/var/run/php/php7.4-fpm.sock;
        fastcgi_index index.php;
        fastcgi_param SCRIPT_FILENAME $realpath_root$fastcgi_script_name;

        fastcgi_buffers 8 16k; # increase the buffer size for PHP-FTP
        fastcgi_buffer_size 32k; # increase the buffer size for PHP-FTP
        fastcgi_connect_timeout 60;
        fastcgi_send_timeout 300;
        fastcgi_read_timeout 300;

        include fastcgi_params;                                                                                                                                >        deny all;
    }
}