django: ошибка "You don’t have permission to view or edit anything."

Только недавно начал изучать Python Django, поэтому не будьте слишком строги.

У меня возникла проблема: я сделал кастомный класс пользователя, но в admin-панели после этого пропали все настройки групп и пользователей; выводится лишь одна надпись "You don’t have permission to view or edit anything."

Вот Model.py:

from django.db import models
from django.contrib.auth.models import AbstractUser, BaseUserManager


class MyUserManager(BaseUserManager):
    def create_user(self, email, username, password=None):
        if not email:
            raise ValueError("Вы не ввили Email")
        if not username:
            raise ValueError("Вы не ввели Логин")

        user = self.model(
            email=self.normalize_email(email),
            username=username,
        )
        user.set_password(password)
        user.save(using=self._db)
        return user

    def create_superuser(self, email, username, password):
        user = self.create_user(
            email=self.normalize_email(email),
            username=username,
            password=password,
        )
        user.is_admit = True
        user.is_staff = True
        user.is_superuser = True
        user.save(using=self._db)
        return user


class User(AbstractUser):
    id = models.AutoField(primary_key=True, unique=True)
    first_name = models.CharField(max_length=50, unique=False)
    last_name = models.CharField(max_length=50, unique=False)
    username = models.CharField(max_length=50, unique=True)
    email = models.EmailField(max_length=100, unique=True)
    is_active = models.BooleanField(default=True)
    is_admin = models.BooleanField(default=False)
    is_staff = models.BooleanField(default=False)
    is_superuser = models.BooleanField(default=False)

    USERNAME_FIELD = 'email'
    REQUIRED_FIELDS = ['username']

    objects = MyUserManager()

    def __str__(self):
        return self.email

    def has_perm(self, perm, obj=None):
        return self.is_admin

    def has_module_perms(self, app_label):
        return True

admin.py:

from django.contrib import admin
from django.contrib.auth.admin import UserAdmin
from users.models import User

admin.site.register(User, UserAdmin)

settings.py:

import os
from configparser import SafeConfigParser

config = SafeConfigParser()
config.read('config.ini')


# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))


# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/3.0/howto/deployment/checklist/

# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = 'w*sp3mf+=zh6ty=d&o9m7r@3v1p4)i5@bedp*mi7z=8tc=ug3j'

# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True

ALLOWED_HOSTS = []

# Application definition

INSTALLED_APPS = [
    'users',
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'rest_framework',
]

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]

ADMIN_VIEW_PERMISSION_MODELS = [
    'auth.User',
]

# AUTHENTICATION_BACKENDS = (
#     ('django.contrib.auth.backends.ModelBackend'),
# )

ROOT_URLCONF = 'socnetproject.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [],
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

AUTH_USER_MODEL = 'users.User'

SITE_ID=1

WSGI_APPLICATION = 'socnetproject.wsgi.application'


# Database
# https://docs.djangoproject.com/en/3.0/ref/settings/#databases

DATABASES = {
    'default': {
        'ENGINE': config.get('database', 'ENGINE'),
        'NAME': config.get('database', 'NAME'),
        'USER' : config.get('database', 'USER'),
        'PASSWORD' : config.get('database', 'PASSWORD'),
        'HOST' : config.get('database', 'HOST'),
        'PORT' : config.get('database', 'PORT'),
    }
}


# Password validation
# https://docs.djangoproject.com/en/3.0/ref/settings/#auth-password-validators

AUTH_PASSWORD_VALIDATORS = [
    {
        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]


# Internationalization
# https://docs.djangoproject.com/en/3.0/topics/i18n/

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_L10N = True

USE_TZ = True


# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/3.0/howto/static-files/

STATIC_URL = '/static/'

Если надо, я ещё скину код.

Подскажите, пожалуйста, хотя бы в каком направлении нужно искать, чтобы исправить эту проблему!