Cannot login admin site after custom User model

My custom user model

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

# Create your models here.
class mUserManager(BaseUserManager):
    def create_user(self, email, username, password = None):
        if not email:
            raise ValueError("Users must have an email address")
        if not username:
            raise ValueError("Users must have an username")

        user = self.model(
            email = self.normalize_email(email),
            username = username,

        return user

    def create_superuser(self, email, username, password=None):
        u = self.create_user(
            email = self.normalize_email(email),
            username = username,

        u.is_admin = True
        u.is_staff = True
        u.is_superuser = True
        u.is_active = True
        return u
class mUser(AbstractBaseUser, PermissionsMixin):
    email                   = models.EmailField(verbose_name="email", max_length=60, 
    username                = models.CharField(max_length=30, unique=True)
    date_joined             = models.DateTimeField(verbose_name='date joined', 
    last_login              = models.DateTimeField(verbose_name='last login', 
    is_admin                = models.BooleanField(default=False)
    is_active               = models.BooleanField(default=False)
    is_staff                = models.BooleanField(default=False)
    is_superuser            = models.BooleanField(default=False)
    password                = models.CharField(max_length=20)
    first_name              = models.CharField(max_length=20)
    last_name              = models.CharField(max_length=20)

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

    objects = mUserManager()

    def __str__(self):

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

    def has_module_perms(self, app_label):
        return True

And in, I add this:

AUTH_USER_MODEL = 'accounts.mUser'

i run makemigrations ad migrate , then createsuperuser , but i cannot login to admin site. I check the database and find the password seems to have no value (in the database, password is pbkdf2_sha256$216000 , it seems like an empty password, *in the image )

One of the problems is that you have set a max_length on your password field of 20 characters - where as you can see, it’s not nearly long enough for the encrypted version. (The string pbkdf2_sha256$216000 is 20 characters long.)
The default password field in AbstractBaseUser is 128 characters in length.

Thank you, i removed it