the user created in the admin panel cannot log in to the admin panel

Question

I have a custom user model:

class CustomUser(AbstractUser):
    ACCESS_LEVELS = (
        ('user', 'Авторизованный пользователь'),
        ('admin', 'Администратор')
    )
    email = models.EmailField(
        max_length=254,
        unique=True,
        verbose_name='Эл. почта'
    )
    access_level = models.CharField(
        max_length=150,
        choices=ACCESS_LEVELS,
        blank=True,
        default='user',
        verbose_name='Уровень доступа',
    )

    @property
    def is_admin(self):
        return self.is_superuser or self.access_level == 'admin'

    class Meta:
        verbose_name = 'Пользователь'
        verbose_name_plural = 'Пользователи'

    def __str__(self):
        return (
            f'email: {self.email}, '
            f'access_level: {self.access_level}'
        )

Registered in the admin panel:

@admin.register(CustomUser)
class UserAdmin(admin.ModelAdmin):
    list_display = ('username', 'email', 'access_level')
    search_fields = ('email', 'access_level')
    list_filter = ('email',)

    def save_model(self, request, obj, form, change):
        if obj.is_admin:
            obj.is_staff = True
        obj.save()

When I create a superuser or a user with staff status and try to log in, a message appears: Please enter the correct username and password for a staff account. Note that both fields may be case-sensitive.

So I Googled the issue and tried everything I could. Here are all the problems I investigated:

Database not synced: I synced it and nothing changed.

No django_session table: I checked; it's there.

Problematic settings: I just added the created apps to INSTALLED_APPS.

User not configured correctly: is_staff, is_superuser, and is_active are all True.

Old sessions: I checked the django_session table and it's empty.

Missing or wrong URL pattern: Currently I have url('admin/', admin.site.urls) in mysite/urls.py.

Wrong server command: I'm using python manage.py runserver.

Something wrong with database: I tried deleting the database and then reapplying the migrations, but nothing changed.

Answer 1

Use UserAdmin^{[Django-GitHub]} to register UserModel. It will provide the functionality to hash the password when you enter the password in admin panel so:

from django.contrib.auth.admin import UserAdmin
from .models import CustomUser

class CustomUserAdmin(UserAdmin):
    pass

admin.site.register(CustomUser, CustomUserAdmin)