Fixed #19077, #19079 -- Made USERNAME_FIELD a required field, and modified UserAdmin to match.

        {% if user.is_active and user.is_staff %}

        <div id="user-tools">

            {% trans 'Welcome,' %}

            <strong>{% filter force_escape %}{% firstof user.get_short_name user.username %}{% endfilter %}</strong>.

            <strong>{% filter force_escape %}{% firstof user.get_short_name user.get_username %}{% endfilter %}</strong>.

            {% block userlinks %}

                {% url 'django-admindocs-docroot' as docsroot %}

                {% if docsroot %}

        {% for action in action_list %}

        <tr>

            <th scope="row">{{ action.action_time|date:"DATETIME_FORMAT" }}</th>

            <td>{{ action.user.username }}{% if action.user.get_full_name %} ({{ action.user.get_full_name }}){% endif %}</td>

            <td>{{ action.user.get_username }}{% if action.user.get_full_name %} ({{ action.user.get_full_name }}){% endif %}</td>

            <td>{{ action.change_message }}</td>

        </tr>

        {% endfor %}

{% block reset_link %}

{{ protocol }}://{{ domain }}{% url 'django.contrib.auth.views.password_reset_confirm' uidb36=uid token=token %}

{% endblock %}

{% trans "Your username, in case you've forgotten:" %} {{ user.username }}

{% trans "Your username, in case you've forgotten:" %} {{ user.get_username }}

{% trans "Thanks for using our site!" %}

from django.template.response import TemplateResponse

from django.utils.html import escape

from django.utils.decorators import method_decorator

from django.utils.safestring import mark_safe

from django.utils import six

from django.utils.translation import ugettext, ugettext_lazy as _

from django.views.decorators.csrf import csrf_protect

from django.views.decorators.debug import sensitive_post_parameters

csrf_protect_m = method_decorator(csrf_protect)

class GroupAdmin(admin.ModelAdmin):

    search_fields = ('name',)

    ordering = ('name',)

            raise PermissionDenied

        if extra_context is None:

            extra_context = {}

        username_field = self.model._meta.get_field(self.model.USERNAME_FIELD)

        defaults = {

            'auto_populated_fields': (),

            'username_help_text': self.model._meta.get_field('username').help_text,

            'username_help_text': username_field.help_text,

        }

        extra_context.update(defaults)

        return super(UserAdmin, self).add_view(request, form_url,

admin.site.register(Group, GroupAdmin)

admin.site.register(User, UserAdmin)

        # built-in safeguards for multiple threads.

        if self.create_unknown_user:

            user, created = UserModel.objects.get_or_create(**{

                getattr(UserModel, 'USERNAME_FIELD', 'username'): username

                UserModel.USERNAME_FIELD: username

            })

            if created:

                user = self.configure_user(user)