For Windows users
The page and resource that was selected as the answer in this post led to a broken page. However, try the code below.
Set debug mode using
$env:FLASK_ENV = "development"
Run app
flask run
[This post solved it for me][1]
[1]: https://stackoverflow.com/a/65899307/11737951
Or
Set it directly from the app in your code.
if __name__ == '__main__':
app.debug = True
app.run(host='0.0.0.0', port=3000)