sometimes give me "anonymoususer" error

[verico1]

from django.http import HttpResponse, request
from django.shortcuts import redirect, get_object_or_404, render
from zeep import Client
from django.conf import settings
from accounts.models import Profile
from products.models import Product
from pay.models import Order, OrderItem
import datetime
from django.core.mail import BadHeaderError, send_mail
from django.template.loader import render_to_string
from pay.views import get_user_pending_order

MERCHANT = 'xxx...xxx'
client = Client('https://www.zarinpal.com/pg/services/WebGate/wsdl')
amount = ""
description = ""  # Required
email = ""  # Optional
mobile = "" # Optional
CallbackURL = 'https://mysite/payment/verify/' # Important: need to edit for realy server.

def send_request(request):
    username = request.user
    amount = get_user_pending_order(request).get_total() + get_user_pending_order(request).transport.transport_price
    email = username.email  # Optional
    mobile = username.profile.phone_number  # Optional
    result = client.service.PaymentRequest(MERCHANT, amount, description, email, mobile, CallbackURL)
    order_to_purchase = get_user_pending_order(request)
    order_to_purchase.save()
    if result.Status == 100:
        return redirect('https://www.zarinpal.com/pg/StartPay/' + str(result.Authority))
    else:
        return HttpResponse('Error code: ' + str(result.Status))

def verify(request):
    amount = get_user_pending_order(request).get_total() + get_user_pending_order(request).transport.transport_price
    if request.GET.get('Status') == 'OK':
        result = client.service.PaymentVerification(MERCHANT, request.GET['Authority'], amount)
        if result.Status == 100:
            user = request.user
            order_to_purchase = get_user_pending_order(request)
            order_to_purchase.is_ordered = True
            order_to_purchase.save()
            order_to_purchase.date_ordered=datetime.datetime.now()
            order_to_purchase.created_on_time=datetime.datetime.now()
            order_to_purchase.save()
            order_items = order_to_purchase.items.all()
            for order_item in order_items:
                order_item.product.quantity = order_item.product.quantity - 1
                order_item.product.save()
            order_items.update(is_ordered=True, date_ordered=datetime.datetime.now())
            subject = 'پرداخت با موفقیت انجام شد'
            c = {
            "refid":str(result.RefID),
            "ref_code":order_to_purchase.ref_code,
            "owner":order_to_purchase.owner,
            }
            email_template_name = "pay/after_pay_confirm_email.html"
            email_html = render_to_string(email_template_name, c)
            email_from = settings.EMAIL_HOST_USER
            send_mail(subject, email_html, email_from, [user.email], html_message=email_html)
            ctx = {'message_good':'پرداخت با موفقیت انجام شد. \n کد پیگیری تراکنش : ' + str(result.RefID)}
        elif result.Status == 101:
            return HttpResponse('Transaction submitted : ' + str(result.Status))
        else:
            return HttpResponse('Transaction failed.\nStatus: ' + str(result.Status))
    else:
        ctx = {'message_bad':'پرداخت با مشکل مواجه شده است یا توسط کاربر لغو شده'}
    return render(request, 'pay/verify.html', ctx)

additional codes :

`def get_user_pending_order(request):
    user_profile = get_object_or_404(Profile, user=request.user)
    order = Order.objects.filter(owner=user_profile, is_ordered=False)
    if order.exists():
        return order[0]
    return 0`

and

class Order(models.Model):
    ...
    owner = models.ForeignKey(Profile, on_delete=models.SET_NULL, null=True)
    is_ordered = models.BooleanField(default=False)
    transport = models.ForeignKey(Transport, on_delete=models.SET_NULL, null=True)
    ...

    def get_cart_items(self):
        return self.items.all()

    def __str__(self):
        return '{0} - {1}'.format(self.owner, self.ref_code)  

    def get_total(self):
        total = 0
        for order_item in self.items.all():
            total += order_item.get_final_price()
        return total

in the beginning of verify get_user_pending_order(request).get_total() + get_user_pending_order(request).transport.transport_price about requests

sometimes with different users give me "anonymoususer" error, not always and its after success payment