Question: I have a navigation menu (header menu) in my web page which is actually takes dynamic content. The dynamic menu items are loaded into `ul>li>{dynamic_content}`. I want this navigation bar (I mean the `ul` ) in the **center** of the section, not vertically but horizontally. I can have `text-align:center` because it has multiple children tags.

Also I can't do the following,

```
.class{
  width:50%;
  margin-left:auto;
  margin-right:auto;
 }

```

because I can't set a `width` since this is a DYNAMIC navigation.

You may think why I can't try

```
.class{
  position:absolute;
  left:50%;
  transform:translateX(-50%);
 }

```

This is also can not be done, because I can't set the `position:absolute` since it's going to be a fixed header on scroll. It make some position problems in responsive.

I'm looking for an alternative to solve this problem.

Answer: 
This is almost certainly because of this backwards-incompatible [change in Django 2.1](https://docs.djangoproject.com/en/2.1/releases/2.1/#features-removed-in-2-1):

> 
> * Support for `Widget.render()` methods without the `renderer` argument is removed.
> 
> 
> 

You may have subclassed `django.forms.widgets.Widget` in your code, or in the code of one of your dependencies. The code may look like this:

```
from django.forms import widgets

class ExampleWidget(widgets.Widget):
    def render(self, name, value, attrs=None):
        # ...

```

You need to fix the method signature of `render`, so that it looks like this:

```
    def render(self, name, value, attrs=None, renderer=None):

```

Have a look at [the source code of `widgets.Widget`](https://github.com/django/django/blob/master/django/forms/widgets.py) if you want to check.
Django is looking for a default renderer which can be set in `settings.py`

```
FORM_RENDERER = 'django.forms.renderers.DjangoTemplates'

```