[Python] Django signals @receiver POST_SAVE not working on PROD (ok on DEV)

Getting nuts ... On dev, my signals (for sending an alert by mail) works for all save (create + update) and delete. But on prod, only delete action sends an email. I didn't notice at once delete signals were working so I spent much time looking for an issue caused by firewall (blocked email outgoing).

Post Save

@receiver(post_save, sender=Navette)
def alerte(sender, instance, created, **kwargs):
ref = instance.ref
user = instance.user.username

if created:
alert(pour=['tintin@gmail.com'],
sujet=f'Nouvelle navette pour la référence {ref} créé par {user}')
else:
alert(pour=['tintin@gmail.com'],
sujet=f'Mise à jour de la navette pour la référence {ref} par {user}')


Post Delete

@receiver(post_delete, sender=Navette)
def alerte(sender, instance, **kwargs):
ref = instance.ref
user = instance.user
alert(pour=['tintin@gmail.com'],
sujet=f'La navette pour la référence {ref} a été supprimée par {user}')


just for info : alert.py

def alert(**kwargs):

#ref = kwargs.get('ref', 'noref')
de = kwargs.get('de', 'toto@gmail.com')
pour = kwargs.get('pour', 'tintin@gmail.com')
sujet = kwargs.get('sujet', 'Sujet Général')
contenu = kwargs.get('contenu', 'cf. objet du mail')
fichier = kwargs.get('fichier', '')

host = 'smtp.gmail.com'
port = 465
user = settings.EMAIL_HOST_USER
passw = settings.EMAIL_HOST_PASSWORD

msg = EmailMessage()
msg['Subject'] = sujet
msg['From'] = de
msg['To'] = pour
msg.set_content('HTML uniquement')

msg.add_alternative(contenu, subtype='html')

with smtplib.SMTP_SSL(host, port) as smtp:
smtp.login(user, passw)
smtp.send_message(msg)


As said almost everywhere, I declared my app not just with its name in settings.py : 'navette.apps.NavetteConfig', and registrered the app config in its __init__ -> default_app_config = 'navette.apps.ActivityAppConfig' even if I thought Ik heard it was not necessary anymore on DJANGO 3.

Finally, heres my apps.py for this app

from django.apps import AppConfig


class NavetteConfig(AppConfig):
default_auto_field = 'django.db.models.BigAutoField'
name = 'navette'

def ready(self):
import navette.signals


Any idea ?

EDIT

navette.views

@login_required
def NavetteCreateView(request):
form = NavetteDetailForm(request.POST)
if request.method == 'POST':
form = NavetteDetailForm(request.POST)
if form.is_valid():
form.save()
navette_ref = form.cleaned_data.get('ref')
logr.debug(f'{navette_ref} - enregistrée')
messages.success(
request, f'La navette {navette_ref} a bien
été créée.')
return redirect('/navettes')
else:
form = NavetteDetailForm()

context = {'form': form, 'title': 'Nouvelle Navette'}
return render(request, 'navette/navette_form.html',
context)


I checked the form_valid -> True

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