Invalid Django form after . read()

Question

My code is like this

Em Views:

def cadastrar(request):
    if request.method == 'POST':
        arquivo = request.FILES["imagem"]
        leitura = arquivo.read()
            if form.is_valid():
                form.save()

The form is saved only if the command leitura = arquivo.read() be commented #.

If it is not commented, after the execution of that line, the form is invalid.

Does anyone know why this is happening?

I’m using Django 3.2.3