Raw "Internal Server Error" for specific URL

I’m getting a raw Internal Server Error page only for one URL in my app and there is no log output for it.

I’ve tested the page locally and can’t find the issue. The raw error page looks like something that the proxy is generating, it’s not an error page from my app (Django).

I’ve tried re-starting the app but that hasn’t helped. It’s strange that it’s only the one URL and that there is nothing in the logs.

Any thoughts on how I could debug this more?

Resolved by turning on debug logging in my app.