运行环境：debia10，python3.7
安装或者升级到7.1.4 ，运行seahub，从控制台看是正常启动的，但web访问都有问题，提示
看对应的 seahub.log,相应内容是：
2020-08-25 15:31:02,669 [ERROR] django.request:135 handle_uncaught_exception Internal Server Error: /accounts/login/
Traceback (most recent call last):
File "/home/master/xdsnet/seafile-server-7.1.4/seahub/thirdpart/django/core/handlers/exception.py", line 41, in inner
response = get_response(request)
File "/home/master/xdsnet/seafile-server-7.1.4/seahub/thirdpart/django/core/handlers/base.py", line 249, in _legacy_get_response
response = self._get_response(request)
File "/home/master/xdsnet/seafile-server-7.1.4/seahub/thirdpart/django/core/handlers/base.py", line 187, in _get_response
response = self.process_exception_by_middleware(e, request)
File "/home/master/xdsnet/seafile-server-7.1.4/seahub/thirdpart/django/core/handlers/base.py", line 185, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/master/xdsnet/seafile-server-7.1.4/seahub/thirdpart/django/utils/decorators.py", line 149, in _wrapped_view
response = view_func(request, *args, **kwargs)
File "/home/master/xdsnet/seafile-server-7.1.4/seahub/thirdpart/django/views/decorators/cache.py", line 57, in _wrapped_view_func
response = view_func(request, *args, **kwargs)
File "/home/master/xdsnet/seafile-server-7.1.4/seahub/seahub/auth/views.py", line 205, in login
'login_bg_image_path': login_bg_image_path,
File "/home/master/xdsnet/seafile-server-7.1.4/seahub/thirdpart/django/shortcuts.py", line 30, in render
content = loader.render_to_string(template_name, context, request, using=using)
File "/home/master/xdsnet/seafile-server-7.1.4/seahub/thirdpart/django/template/loader.py", line 68, in render_to_string
return template.render(context, request)
File "/home/master/xdsnet/seafile-server-7.1.4/seahub/thirdpart/django/template/backends/django.py", line 66, in render
return self.template.render(context)
File "/home/master/xdsnet/seafile-server-7.1.4/seahub/thirdpart/django/template/base.py", line 205, in render
with context.bind_template(self):
File "/usr/lib/python3.7/contextlib.py", line 112, in __enter__
return next(self.gen)
File "/home/master/xdsnet/seafile-server-7.1.4/seahub/thirdpart/django/template/context.py", line 263, in bind_template
updates.update(processor(self.request))
File "/home/master/xdsnet/seafile-server-7.1.4/seahub/seahub/base/context_processors.py", line 71, in base
if not file_server_root.endswith('/'):
AttributeError: 'NoneType' object has no attribute 'endswith'
这个要怎么解决？