Getting Always Online to work with Heroku

Hello Mr. Community!

I am trying to get my Heroku app HTML pages to work while the origin is “unreachable”.

I have enabled Always Online about 2 months ago, and looking at the Internet Archive it seems that the landing page is correctly cached/archived 4 times (latest one on 25 Jan): https://web.archive.org/web/20230125131042/https://bitmenu.ro/

However, I have now turned off my Heroku app but it seems like Cloudflare Always Online is not serving this page: https://bitmenu.ro/

Is there a definition for what “unreachable” means to Cloudflare? Because by looking at the logs I do indeed see a 503 for the initial bitmenu.ro HTML, and then a 200 for the application-error.html.

Does this 503+200 returned by Heroku cause CF to think the site is up?
If yes, is there any way to configure CF to not think that? Or Heroku even as far as you know?

Thanks!

Yes. Always offline is only activated when the origin is unreachable. Your origin is reachable, but throwing an error.

None that I am aware of. Cloudflare only cares about that your origin is reachable.