I was using the OpenID Connect playground with a custom template and everything works fine. I received a code and decided to use it in Postman. When I use the exact same request parameters as the example from the “Exchange Code from Token”, the server returns a bad request.
The authentication code was accepted, but the request failed in a later stage. Turns out the server expects “redirect_uri” instead of “redirect_url” (playground uses "redirect_uri"in the background)