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django.db.utils.IntegrityError: UNIQUE constraint failed: new__vacancies_company.owner_id error

I try to migrate and an error occurs:

django.db.utils.IntegrityError: UNIQUE constraint failed: new__vacancies_company.owner_id

from django.db import models
from django.contrib.auth.models import User
class Company(models.Model):
    name = models.CharField(max_length=64)
    location = models.CharField(max_length=64)
    logo = models.ImageField(upload_to="MEDIA_COMPANY_IMAGE_DIR")
    description = models.TextField()
    employee_count = models.IntegerField()
    owner = models.OneToOneField(User, on_delete=models.CASCADE, related_name="owner_user")
class Specialty(models.Model):
    code = models.CharField(max_length=32)
    title = models.CharField(max_length=32)
    picture = models.ImageField(upload_to="MEDIA_SPECIALITY_IMAGE_DIR")
class Vacancy(models.Model):
    title = models.CharField(max_length=100)
    specialty = models.ForeignKey(Specialty, on_delete=models.CASCADE, related_name="vacancies")
    company = models.ForeignKey(Company, on_delete=models.CASCADE, related_name="vacancies")
    skills = models.TextField()
    description = models.TextField()
    salary_min = models.FloatField()
    salary_max = models.FloatField()
    published_at = models.DateTimeField()
class Application(models.Model):
    written_username = models.CharField(max_length=24)
    written_phone = models.CharField(max_length=12)
    written_cover_letter = models.CharField(max_length=300)
    vacancy = models.ForeignKey(Vacancy, on_delete=models.CASCADE, related_name="applications")
    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name="applications")
python manage.py runserver result:
OperationalError at /
no such column: vacancies_company.owner_id
this happen to me when i try to add new models with foreign keys and the old models already have some data in them. if that is the case:
what i do is :
comment the new models
runserver
delete every data in my models in the admin page
uncomment the new models
makemigration and migrate
if it persists
redo steps and re-create superuser
if still
delete the database file (sqlite file from directory)
in you app delete migrations except (init.py) file
makemigration and migrate
that is usually how i treat it , hope thay'll help
If you have had ForeignKey before, and now changed to OneToOneField,
If you have used python3 manage.py migrate --fake before and now you added an new field to your model with the OneToOneField
Solution 1.
Change the OneToOneField back to a ForeignKey
Solution 2.
python3 manage.py migrate --fake
and then go to the admin page and make sure that the owner is unique, meaning that all the users that has a company is owner for only 1 company. If a user is owner for 2 or more companies, then you can delete that company which has an owner with 2 or more companies, or go to Solution 1, since OneToOneField means that you only can have 1 owner which is a User for 1 company. So if a user is owner for 2 companies or more, then it will give you that error.
        
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