TypeError: startswith first arg must be bytes or a tuple of bytes, not str

[ghost]

I'm trying to create a new model, nothing strange, some ForeignKey to CharField is the strangest.
When I try to migrate, this error is shown:

File "manage.py", line 18, in
execute_from_command_line(sys.argv)
File "/project_folder/venv3/lib/python3.6/site-packages/django/core/management/init.py", line 381, in execute_from_command_line
utility.execute()
File "/project_folder/venv3/lib/python3.6/site-packages/django/core/management/init.py", line 375, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/project_folder/venv3/lib/python3.6/site-packages/django/core/management/base.py", line 316, in run_from_argv
self.execute(*args, **cmd_options)
File "/project_folder/venv3/lib/python3.6/site-packages/django/core/management/base.py", line 353, in execute
output = self.handle(*args, **options)
File "/project_folder/venv3/lib/python3.6/site-packages/django/core/management/base.py", line 83, in wrapped
res = handle_func(*args, **kwargs)
File "/project_folder/venv3/lib/python3.6/site-packages/django/core/management/commands/migrate.py", line 203, in handle
fake_initial=fake_initial,
File "/project_folder/venv3/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 "/project_folder/venv3/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 "/project_folder/venv3/lib/python3.6/site-packages/django/db/migrations/executor.py", line 244, in apply_migration
state = migration.apply(state, schema_editor)
File "/project_folder/venv3/lib/python3.6/site-packages/django/db/backends/base/schema.py", line 106, in exit
self.execute(sql)
File "/project_folder/venv3/lib/python3.6/site-packages/sql_server/pyodbc/schema.py", line 642, in execute
sql = str(sql)
File "/project_folder/venv3/lib/python3.6/site-packages/django/db/backends/ddl_references.py", line 175, in str
return self.template % self.parts
File "/project_folder/venv3/lib/python3.6/site-packages/django/db/backends/ddl_references.py", line 91, in str
return ', '.join(col_str(column, idx) for idx, column in enumerate(self.columns))
File "/project_folder/venv3/lib/python3.6/site-packages/django/db/backends/ddl_references.py", line 91, in
return ', '.join(col_str(column, idx) for idx, column in enumerate(self.columns))
File "/project_folder/venv3/lib/python3.6/site-packages/django/db/backends/ddl_references.py", line 87, in col_str
return self.quote_name(column) + self.col_suffixes[idx]
File "/project_folder/venv3/lib/python3.6/site-packages/django/db/backends/base/schema.py", line 136, in quote_name
return self.connection.ops.quote_name(name)
File "/project_folder/venv3/lib/python3.6/site-packages/sql_server/pyodbc/operations.py", line 246, in quote_name
if name.startswith('[') and name.endswith(']'):
TypeError: startswith first arg must be bytes or a tuple of bytes, not str

A you can see, I am using django 2.1.5 and python 3.6