Currently we include the following block for a few 500-level errors:
error_page 500 502 504 /500.html;
location = /500.html {
root {{ project_path }}/{{ application_name }}/templates/;
}
However, this seems project-specific. My suggestion is to remove this block and allow users to manage 500-level errors that aren't 503 (Service Unavailable, related to the maintenance page) themselves.