django.db.utils.InternalError: (1050, "Table 'django_content_type' already exists")

Question

django.db.utils.InternalError: (1050, "Table 'django_content_type' already exists")

I just copied a project from my friend, when I run makemirations it runs properly. But for -

python3 manage.py migrate 

it gives this error -

Operations to perform:
  Apply all migrations: admin, auth, balancesheet, contenttypes, dynapp, pandl2, sessions, trialbal2
Running migrations:
  Applying contenttypes.0001_initial...Traceback (most recent call last):
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/db/backends/utils.py", line 82, in _execute
    return self.cursor.execute(sql)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/db/backends/mysql/base.py", line 74, in execute
    return self.cursor.execute(query, args)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/pymysql/cursors.py", line 170, in execute
    result = self._query(query)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/pymysql/cursors.py", line 328, in _query
    conn.query(q)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/pymysql/connections.py", line 517, in query
    self._affected_rows = self._read_query_result(unbuffered=unbuffered)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/pymysql/connections.py", line 732, in _read_query_result
    result.read()
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/pymysql/connections.py", line 1075, in read
    first_packet = self.connection._read_packet()
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/pymysql/connections.py", line 684, in _read_packet
    packet.check_error()
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/pymysql/protocol.py", line 220, in check_error
    err.raise_mysql_exception(self._data)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/pymysql/err.py", line 109, in raise_mysql_exception
    raise errorclass(errno, errval)
pymysql.err.InternalError: (1050, "Table 'django_content_type' already exists")

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "manage.py", line 21, in <module>
    main()
  File "manage.py", line 17, in main
    execute_from_command_line(sys.argv)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/core/management/__init__.py", line 375, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/core/management/base.py", line 323, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/core/management/base.py", line 364, in execute
    output = self.handle(*args, **options)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/core/management/base.py", line 83, in wrapped
    res = handle_func(*args, **kwargs)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/core/management/commands/migrate.py", line 234, in handle
    fake_initial=fake_initial,
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/db/migrations/executor.py", line 117, in migrate
    state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/db/migrations/executor.py", line 147, in _migrate_all_forwards
    state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/db/migrations/executor.py", line 245, in apply_migration
    state = migration.apply(state, schema_editor)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/db/migrations/migration.py", line 124, in apply
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/db/migrations/operations/models.py", line 92, in database_forwards
    schema_editor.create_model(model)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/db/backends/base/schema.py", line 307, in create_model
    self.execute(sql, params or None)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/db/backends/base/schema.py", line 137, in execute
    cursor.execute(sql, params)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/db/backends/utils.py", line 99, in execute
    return super().execute(sql, params)
  File "/home/hostbooks/django1/myproject/lib/python3.6/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/hostbooks/django1/myproject/lib/python3.6/site-packages/django/db/backends/utils.py", line 76, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/db/backends/utils.py", line 82, in _execute
    return self.cursor.execute(sql)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/django/db/backends/mysql/base.py", line 74, in execute
    return self.cursor.execute(query, args)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/pymysql/cursors.py", line 170, in execute
    result = self._query(query)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/pymysql/cursors.py", line 328, in _query
    conn.query(q)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/pymysql/connections.py", line 517, in query
    self._affected_rows = self._read_query_result(unbuffered=unbuffered)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/pymysql/connections.py", line 732, in _read_query_result
    result.read()
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/pymysql/connections.py", line 1075, in read
    first_packet = self.connection._read_packet()
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/pymysql/connections.py", line 684, in _read_packet
    packet.check_error()
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/pymysql/protocol.py", line 220, in check_error
    err.raise_mysql_exception(self._data)
  File "/home/hostbooks/django1/myproject/lib/python3.6/site-packages/pymysql/err.py", line 109, in raise_mysql_exception
    raise errorclass(errno, errval)
django.db.utils.InternalError: (1050, "Table 'django_content_type' already exists")


 django.db.utils.InternalError: (1050, "Table 'django_content_type' already exists")

When I opened MySQL to delete 'DJANGO_CONTENT_TYPE table with drop table command, it gives this error -

mysql> drop table django_content_type;
ERROR 1217 (23000): Cannot delete or update a parent row: a foreign key constraint fails

Ie I cant delete this table.

I did migrations because I did some changes in model.

Though I found an alternative to bypass this error not by logic. I created a nee database and changed settings to new database. Here I copied the content from initial database to another.

Answer 1

For django3: I get this error: django.db.utils.OperationalError: (1054, "Unknown column 'name' in 'django_content_type'")

1. Delete myapp/migrations/0001_initial.py and 0002_ .....

2. Delete all rows from the django_migrations table.

    Delete * from django_migrations

3. python3 manage.py makemigrations

or

python manage.py makemigrations

4. python3 manage.py migrate --fake-initial

or

python manage.py migrate --fake-initial

5. I get this error: MySQLdb._exceptions.OperationalError: (1054, "Unknown column 'name' in 'django_content_type'")

6. I add a column to django_content_type table.

   alter table django_content_type add name varchar(255)

7. python3 manage.py migrate --fake-initial

8. This error appears django.db.utils.OperationalError: (1061, "Duplicate key name 'django_site_domain_a2e37b91_uniq'")

9. I did not do anything about this error but my website works perfectly. 'name' column will remove

Answer 2

通过首先从我的应用程序中删除 database 、 migration 和pycache ，最后删除我的 virtualenv 并创建一个新的，我的问题得到了解决。