Basic clean wordpress install on Nginx returns 502 error - wordpress

Question

I’m learning about running a server on a raspberry pi and just want to run a simple default wordpress site served with Nginx. For some reason loading the site locally in a browser returns a 502 error despite my other basic non-wordpress sites loading correctly. A clean download of the default wordpress installation files are inside /var/www/wp.example.co.uk
I’ve made a wp.example.co.uk.conf file inside /etc/nginx/sites-available - also symlinked to /etc/nginx/sites-enabled - with the code:
upstream wp-php-handler {
server unix:/var/run/php/php7.3-fpm.sock;
}
server {
listen 5432;
server_name _;
root /var/www/wp.example.co.uk;
index index.php;
location / {
try_files $uri $uri/ /index.php?$args;
}
location ~ \.php$ {
include snippets/fastcgi-php.conf;
fastcgi_pass wp-php-handler;
}
}
Whenever I view it in a browser (http://mylocalip:4323) it returns a 502 error. Why does this happen?
Note: I’m following a YouTube tutorial (where the relevant part is ~6:43 of https://www.youtube.com/watch?v=8psimaAr1U8) that shows the same code working, which leads me to believe that my code should work as-is.
Thanks

Answer 1

It looks like the tutorial might be outdated after only 6 months. It tells you to install php-fpm, and then it just assumes that version 7.3 is going to be installed. If you run the command apt show php-fpm | grep "Depends:" it'll tell you which version is actually being installed. Now while you could just run apt install php7.3-fpm to follow along with the tutorial, I've included some instructions below on how to use a more recent version of PHP.
Install the version you want e.g. apt install php8.1-fpm or just apt install php-fpm for the current default version.
Run ls -d /var/run/php/* | grep sock --color=never to view all of the versions of PHP-fpm that are available on your system for you to use. The version that you just installed should be listed here.
In the line of your config file that says server unix:/var/run/php/php7.3-fpm.sock;, replace the file referenced with one of the files listed in step 2.
Don't forget to reload Nginx when done. On Ubuntu and Debian systems this is done with the command sudo systemctl reload nginx.