In the same page about utcfromtimestamp https://docs.python.org/3.7/library/datetime.html#datetime.datetime.utcfromtimestamp it says:

> with tzinfo None

Also below, "To get an aware datetime object". All this means or implies naïve object.

I've no idea what you mean by "fails silently". In what way does astimezone fail silently. You have your naïve object, then you convert it aware object, then to a different timezone. What is the problem here?