Error while trying to migrate database (slalchemy, slqite3)

I have the next models.py file:

from app import db, bcrypt
from sqlalchemy import ForeignKey
from sqlalchemy.orm import relationship


class BlogPost(db.Model):

    __tablename__ = "posts"

    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String, nullable=False)
    desc = db.Column(db.String, nullable=False)
    author_id = db.Column(db.Integer, ForeignKey('users.id'))

    def __init__(self, title, desc):
        self.title = title
        self.desc = desc

    def __repr__(self):
        return "Titulo >> " + self.title

class User(db.Model):

    __tablename__ = 'users'

    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String, nullable=False)
    email = db.Column(db.String, nullable=False)
    password = db.Column(db.String, nullable=False)
    posts = relationship("BlogPost", backref="author")

    def __init__(self, name, email, password):
        self.name = name
        self.email = email
        self.password = password

    def __repr__(self):
        return "Usuario >> ", self.name

Then I ran:

python manage.py db init

and everything was fine, the thing is when I tried to modify my models file to make a migration.. I just change the line:

self.password = password

to:

self.password = bcrypt.generate_password_hash(password)

and when I ran:

python manage.py db migrate

it works, but when I tried to upgrade with:

python manage.py db upgrade

I get the next error:

"No support for ALTER of constraints in SQLite dialect")
NotImplementedError: No support for ALTER of constraints in SQLite dialect

Note: the database just has a few records for testing.. thank you!