Cannot upgrade Render plan for web service

3

I tried a couple more things with no success:

  1. I tried changing my app port from 10000 to 26156 to make sure I’m not accidentally hitting a port conflict with anything. No change, port change is fine on Free tier, but health check fails on non-free.

  2. I did some research and found this thread:
    Zero-downtime sane defaults

Which mentions the behavior of Render when no health check is defined. Basically, it should run a port scan.

I deleted my health check path again, and re-deployed on the free tier to check, and I see this in my server log:

Apr 11 12:08:49 PM  [2022-04-11 22:08:49.443] http: GET index.html (66 ms) 200
Apr 11 12:08:49 PM  [2022-04-11 22:08:49.874] http: GET index.html (86 ms) 200

So on the free tier, I can see Render doing the port scan on my application successfully.

I then attempted the plan upgrade again with out the health check path, and I waited.

And I kept waiting. The health check on the non-free tiers for some unknown reason does not reach my application.

Why is this happening?