Session data is lost when using HttpResponseRedirect

Using Django Mystery Errors
1

I have two simple views:

def form_view(request):
    form = MyModelForm()
    if request.method == "POST":
        form = MyModelForm(request.POST)
            if form.is_valid()
                form.save()
                uuid = uuid4()
                request.session["uuid"] = uuid.hex
                return HttpResponseRedirect(reverse("thanks"))
    return render(request, "form.jinja2", {"form": form})

# the url obtained by reverse("thanks") maps to this view
def redirect_view(request):
    if "uuid" in request.session: # this returns false in prodcution
        return render(request, "thanks.jinja2", {"uuid": request.session["uuid"]}
    return redirect("/")

The code works in development, i.e I can fetch data from request.session, but in production it does not work, and I can’t seem to figure out why.

I have tried to set request.session.modified = True, set SESSION_COOKIE_SECURE = False in settings and also tried using request.session.set_test_cookie() and request.session.test_cookie_worked() in the two different views, i.e setting the cookie in form_view and testing the cookie in redirect_view, but it returned false. Interestingly, if I do this:

def form_view(request):
    form = MyModelForm()
    if request.method == "POST":
        print(request.session.test_cookie_worked()) # this prints True!
        form = MyModelForm(request.POST)
            if form.is_valid()
                form.save()
                uuid = uuid4()
                request.session["uuid"] = uuid.hex
                return HttpResponseRedirect(reverse("thanks"))
    request.session.set_test_cookie()
    return render(request, "form.jinja2", {"form": form})

The test_cookie_worked() returns True.

I have tried many of the solutions recommended when searching on something similar, but none of these work for me, and I don’t know what else to try.

Relevant settings for both environments are:

SESSION_COOKIE_SECURE = True
SESSION_EXPIRE_AT_BROWSER_CLOSE = True
SESSION_COOKIE_AGE = 60 * 60
SECURE_SSL_REDIRECT = True
CSRF_COOKIE_SECURE = True
SESSION_ENGINE = 'django.contrib.sessions.backends.db'

Both the production environment and development are running over https.

2

I found a solution. It was a problem with varnish, as it deleted all cookies. I added an exception for the site and it worked.