postgresql - django.db.utils.ProgrammingError: relation does not exist

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I developed a Django application deployed on DigitalOcean's Ubuntu server with Postgres db. Everything worked fine, without any problems, but today after adding new model, I'm getting this error: relation "documents_app_document" does not exist although I have this model, where some of my models inherits from Document model. But somehow it was deleted from database, and now I can't add it back to database after migration. How can I add that model as a table again to database ?

p.s: But I've opened my migration file named '0001_initial.py', there is migrations.CreateModel( name='Document'...

models.py :

class Document(models.Model):
    created_date = models.DateTimeField(default=timezone.now, blank=True, null=True)
    added_by = CurrentUserField()
    purpose = models.CharField(blank=True, max_length=300, null=True)
    def __str__(self):
        return str(self.added_by)
class MedicalDocument(Document):
    policy_number = models.CharField(max_length=20, blank=True, null=True)
    medical_institution = models.CharField(max_length=100, blank=True, null=True) 
Migration error:
Operations to perform:
  Unapply all migrations: documents_app
Running migrations:
  Rendering model states... DONE
  Unapplying documents_app.0001_initial...Traceback (most recent call last):
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
psycopg2.errors.UndefinedTable: relation "documents_app_document" does not exist
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
  File "manage.py", line 22, in <module>
    main()
  File "manage.py", line 18, in main
    execute_from_command_line(sys.argv)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/core/management/__init__.py", line 375, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/core/management/base.py", line 323, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/core/management/base.py", line 364, in execute
    output = self.handle(*args, **options)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/core/management/base.py", line 83, in wrapped
    res = handle_func(*args, **kwargs)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/core/management/commands/migrate.py", line 234, in handle
    fake_initial=fake_initial,
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/migrations/executor.py", line 121, in migrate
    state = self._migrate_all_backwards(plan, full_plan, fake=fake)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/migrations/executor.py", line 196, in _migrate_all_backwards
    self.unapply_migration(states[migration], migration, fake=fake)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/migrations/executor.py", line 269, in unapply_migration
    state = migration.unapply(state, schema_editor)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/migrations/migration.py", line 175, in unapply
    operation.database_backwards(self.app_label, schema_editor, from_state, to_state)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/migrations/operations/fields.py", line 120, in database_backwards
    schema_editor.remove_field(from_model, from_model._meta.get_field(self.name))
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/backends/base/schema.py", line 487, in remove_field
    self.execute(sql)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/backends/base/schema.py", line 137, in execute
    cursor.execute(sql, params)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/backends/utils.py", line 99, in execute
    return super().execute(sql, params)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/backends/utils.py", line 67, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/backends/utils.py", line 76, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
django.db.utils.ProgrammingError: relation "documents_app_document" does not exist
                It would also help to actually add the code of the models and maybe even of the migration(s).
– Glenn D.J.
                Dec 20, 2020 at 17:46
                You don't seem to have a migration that creates the model MedicalDocument. If there's no migration that has this, running makemigrations should create a new migration including it.
– Glenn D.J.
                Dec 20, 2020 at 18:06
After adding changing / adding a new model, always make sure to run python manage.py makemigrations and python manage.py migrate.
If for any reason (migration tree re-arrangement, database failure etc.) something went wrong, you can reverse to a specific migration by doing python manage.py migrate {app_name} {migration_index}.
So what I would suggest in your situation is that you try python manage.py migrate {app_name} zero, and then re-migrate back to the latest version.
You might also need to use --fake.
                I've already did migrations. The command python manage.py migrate {app_name} zero resulted for me again with the same error.
– Bob Reynolds
                Dec 20, 2020 at 20:39
                @BobReynolds Did you try doing it with --fake, and then re-applying it? Sounds like the database state doesn't match the Django migrations state, and using --fake should definitely solve it.
– Dolev Pearl
                Dec 20, 2020 at 20:40
                Please look at my full error report, maybe you'll find some hint. About fake I'll try now. So, what should I do after fake migration ?
– Bob Reynolds
                Dec 20, 2020 at 20:41
                I did have a look, please try with fake. Always works for me and this is pretty much what it's made for. After faking, you should simply run python manage.py migrate without fake, and everything should work fine.
– Dolev Pearl
                Dec 20, 2020 at 20:43
                It worked, man. But on my website (production) still displaying relation "documents_app_document" does not exist
– Bob Reynolds
                Dec 20, 2020 at 20:48
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