Anvil Serialization Error

Thanks Meredydd
this:

The good news is that anvil.http.request() returns a Media object already! So you can just pass your response value into your server function, without calling get_bytes() on it – and then you can call get_bytes() to get the contents in your server function

is indeed the solution to my case.
I still don’t understand why the attempt (see cloned app) to convert the decoding in utf-8 gives error:

csv_string_QIS = response.get_bytes().decode('utf-8')

UnicodeEncodeError: UTF-8 decoding failed

Thanks!