Laravel 502 Bad Gateway Error

Change your fastcgi_pass to 127.0.0.1:9000 in your website's nginx sites_enabled conf file.

If you recently ran sudo apt-get update and installed a new version of PHP, and use nginx, make sure you've updated your fastcgi_pass setting in /etc/nginx/sites-enabled, e.g.:

fastcgi_pass unix:/run/php/php7.3-fpm.sock;

You should also make sure you install the latest version of the pdo_pgsql extension.