Nifty way of redirecting to error pages with nginx, using try_files and named locations.

errors.nginx

server {

  error_page 404  = @notfound;
  
  # You can also connect multiple errors to a location handler.
  error_page 500 502 504 = @something_else;

  # Try whatever paths, end with @notfound
  location / {
    try_files $uri $uri.html $uri.etc /index.html @notfound;
  }

  location @notfound {
    try_files /404.html =404; # =404 is a shortcut to nginx's default error
  }

}