Hi Nicolas Anderson,
Thank you for reaching out to us on the Microsoft Q&A forum.
I completely understand your frustration with the outdated documentation and the difficulties you're facing in completing the lab. I apologize for the inconvenience this has caused.
I want to assure you that we've already reached out to our internal team regarding this issue, and they're working on it. In the meantime, I'd like to provide a reference link that might be helpful in completing the exercise: https://video2.skills-academy.com/en-us/answers/questions/1857097/keep-getting-invalid-body-error-for-function-app-f.
We appreciate your patience and understanding in this matter, and we'll do our best to provide an updated solution as soon as possible.