Deploy to Heroku issues with API

Any ideas on how to fix this? I deployed my spark app to Heroku. Everything is working great until I call my internal Spark API. I'm getting a 500 internal server error.

I made sure to change the APP_URL so that it is the heroku URL, so the call looks like this

[heroku url]/api/v1/...

And it should work. I'm not really sure why it's not working. Are there any other .env settings or spark settings that I need to change for production? Again, all of this works on my local env

A thought here... could it have something to do with https?