I\'ve just recently moved my websites from apache2 to Nginx as my new web server backend. got to love problems aha.
HTML files in the web host director work prior to php
Reinstall php-fpm works for me:
apt-get purge php7.3-fpm rm -rf /etc/php/7.3/fpm/ apt-get install php7.3-fpm service nginx restart service php7.3-fpm restart