AttributeError at /admin/login/ 'MetaDict' object has no attribute 'pk'

[xycfree]

Request Method:	POST
http://127.0.0.1:8007/admin/login/?next=/admin/
1.9
AttributeError
'MetaDict' object has no attribute 'pk'
D:\tools\python36\venv2\lib\site-packages\django\contrib\auth_init_.py in login, line 111
D:\tools\python36\venv2\Scripts\python3.6.exe
3.6.5

[xycfree]

[29/Aug/2018 19:32:28] "POST /api/auth/ HTTP/1.1" 200 6639
[29/Aug/2018 19:34:20] "GET /admin/ HTTP/1.1" 302 0
[29/Aug/2018 19:34:20] "GET /admin/login/?next=/admin/ HTTP/1.1" 200 1679
Internal Server Error: /admin/login/
Traceback (most recent call last):
File "D:\tools\python36\venv2\lib\site-packages\django\core\handlers\base.py", line 149, in get_response
response = self.process_exception_by_middleware(e, request)
File "D:\tools\python36\venv2\lib\site-packages\django\core\handlers\base.py", line 147, in get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "D:\tools\python36\venv2\lib\site-packages\django\views\decorators\cache.py", line 57, in _wrapped_view_func
response = view_func(request, *args, **kwargs)
File "D:\tools\python36\venv2\lib\site-packages\django\contrib\admin\sites.py", line 407, in login
return login(request, **defaults)
File "D:\tools\python36\venv2\lib\site-packages\django\contrib\auth\views.py", line 49, in inner
return func(*args, **kwargs)
File "D:\tools\python36\venv2\lib\site-packages\django\views\decorators\debug.py", line 76, in sensitive_post_parameters_wrapper
return view(request, *args, **kwargs)
File "D:\tools\python36\venv2\lib\site-packages\django\utils\decorators.py", line 149, in _wrapped_view
response = view_func(request, *args, **kwargs)
File "D:\tools\python36\venv2\lib\site-packages\django\views\decorators\cache.py", line 57, in wrapped_view_func
response = view_func(request, *args, **kwargs)
File "D:\tools\python36\venv2\lib\site-packages\django\contrib\auth\views.py", line 76, in login
auth_login(request, form.get_user())
File "D:\tools\python36\venv2\lib\site-packages\django\contrib\auth_init.py", line 111, in login
request.session[SESSION_KEY] = user._meta.pk.value_to_string(user)
AttributeError: 'MetaDict' object has no attribute 'pk'
[29/Aug/2018 19:34:31] "POST /admin/login/?next=/admin/ HTTP/1.1" 500 104218