Не понимаю, в чем ошибка

urlpatterns = [
    path('', views.index, name='index_url'),
    path('<slug:brand>/', views.brand_filter, name='brand_url')


def brand_filter(request, brand):
    brand_product_list = Product.objects.filter(brand=brand)
    current_brand = Brand.objects.get(name=brand)
    return render(request, 'branded.html', {'brand_product_list': brand_product_list, 'current_brand': current_brand})\

Field 'id' expected a number but got 'Fischer'.