DjangoのmodelでTypeError: write() argument must be str, not bytesが出る

Question

Djangoのmodelに

user_screen = models.CharField(max_length=100)

というフィールドを追加して、「python manage.py makemigrations」しようとしたところ、それまで特に問題なかったのですが、

下記のエラーがでました。　（環境はMac、Python3.7.6、Django3.0）

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 "C:\Users\Windows\Documents\pythonfiles\django\venv\tutorial\lib\site-packages\django\core\management\__init__.py", line 401, in execute_from_command_line
    utility.execute()
  File "C:\Users\Windows\Documents\pythonfiles\django\venv\tutorial\lib\site-packages\django\core\management\__init__.py", line 395, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "C:\Users\Windows\Documents\pythonfiles\django\venv\tutorial\lib\site-packages\django\core\management\base.py", line 328, in run_from_argv
    self.execute(*args, **cmd_options)
  File "C:\Users\Windows\Documents\pythonfiles\django\venv\tutorial\lib\site-packages\django\core\management\base.py", line 369, in execute
    output = self.handle(*args, **options)
  File "C:\Users\Windows\Documents\pythonfiles\django\venv\tutorial\lib\site-packages\django\core\management\base.py", line 83, in wrapped
    res = handle_func(*args, **kwargs)
  File "C:\Users\Windows\Documents\pythonfiles\django\venv\tutorial\lib\site-packages\django\core\management\commands\makemigrations.py", line 168, in handle
    migration_name=self.migration_name,
  File "C:\Users\Windows\Documents\pythonfiles\django\venv\tutorial\lib\site-packages\django\db\migrations\autodetector.py", line 43, in changes
    changes = self._detect_changes(convert_apps, graph)
  File "C:\Users\Windows\Documents\pythonfiles\django\venv\tutorial\lib\site-packages\django\db\migrations\autodetector.py", line 185, in _detect_changes
    self.generate_added_fields()
  File "C:\Users\Windows\Documents\pythonfiles\django\venv\tutorial\lib\site-packages\django\db\migrations\autodetector.py", line 850, in generate_added_fields
    self._generate_added_field(app_label, model_name, field_name)
  File "C:\Users\Windows\Documents\pythonfiles\django\venv\tutorial\lib\site-packages\django\db\migrations\autodetector.py", line 871, in _generate_added_field
    field.default = self.questioner.ask_not_null_addition(field_name, model_name)
  File "C:\Users\Windows\Documents\pythonfiles\django\venv\tutorial\lib\site-packages\django\db\migrations\questioner.py", line 153, in ask_not_null_addition
    "Quit, and let me add a default in models.py",
  File "C:\Users\Windows\Documents\pythonfiles\django\venv\tutorial\lib\site-packages\django\db\migrations\questioner.py", line 95, in _choice_input
    print(question)
  File "C:\Users\Windows\AppData\Local\Programs\Python\Python37-32\lib\codecs.py", line 378, in write
    self.stream.write(data)
TypeError: write() argument must be str, not bytes

エラーが起こった時のファイルはこちらです

from django.db import models

# Create your models here.
class TwitterModel(models.Model):

    class Meta:
        #テーブル名の指定
        db_table ="category"

    user_screen = models.CharField(max_length=100)
    user_name = models.CharField(max_length=140)
    user_id = models.CharField(max_length=140)
    user_img = models.CharField(max_length=140)
    user_text = models.TextField(null=True)
    user_created_at = models.CharField(max_length=140)

試してみたこと

user_screen = models.CharField(max_length=100)

を外すと

No changes detected

とのみ表示されてエラーは出ません。

原因がわからないので困っています。

どうぞよろしくお願いいたします。