Custom 404 page for Jigsaw in Laravel Forge

This site is built with Tightens Jigsaw and runs on Laravel Forge. The 404 page did not work out of the box.

Tighten tells you to add error_page 404 /404; to the Nginx config. That is true. But it does not work in Forge.
The solution is to add one more line. fastcgi_intercept_errors on;

# FORGE CONFIG (DO NOT REMOVE!)
include forge-conf/robin.se/server/*;

fastcgi_intercept_errors on;

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; }

access_log off;
error_log  /var/log/nginx/robin.se-error.log error;

error_page 404 /404;

location ~ \.php$ {
    fastcgi_split_path_info ^(.+\.php)(/.+)$;
    fastcgi_pass unix:/var/run/php/php7.2-fpm.sock;
    fastcgi_index index.php;
    include fastcgi_params;
}

Don't forget to restart Nginx!