Django error when trying ot preview a file

I’m seeing these errors when trying to preview a file or trying to open a file with Libreoffice online.

Traceback (most recent call last):
  File "/srv/opentec/seafile-pro-server-7.0.8/seahub/thirdpart/django/core/handlers/exception.py", line 41, in inner
    response = get_response(request)
  File "/srv/opentec/seafile-pro-server-7.0.8/seahub/thirdpart/django/core/handlers/base.py", line 249, in _legacy_get_response
    response = self._get_response(request)
  File "/srv/opentec/seafile-pro-server-7.0.8/seahub/thirdpart/django/core/handlers/base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/srv/opentec/seafile-pro-server-7.0.8/seahub/thirdpart/django/core/handlers/base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/srv/opentec/seafile-pro-server-7.0.8/seahub/seahub/auth/decorators.py", line 70, in _wrapped_view
    return view_func(request, *args, **kwargs)
  File "/srv/opentec/seafile-pro-server-7.0.8/seahub/seahub/thumbnail/views.py", line 56, in thumbnail_create
    success, status_code = generate_thumbnail(request, repo_id, size, path)
  File "/srv/opentec/seafile-pro-server-7.0.8/seahub/seahub/thumbnail/utils.py", line 104, in generate_thumbnail
    os.makedirs(thumbnail_dir)
  File "/usr/lib64/python2.7/os.py", line 150, in makedirs
    makedirs(head, mode)
  File "/usr/lib64/python2.7/os.py", line 150, in makedirs
    makedirs(head, mode)
  File "/usr/lib64/python2.7/os.py", line 150, in makedirs
    makedirs(head, mode)
  File "/usr/lib64/python2.7/os.py", line 150, in makedirs
    makedirs(head, mode)
  File "/usr/lib64/python2.7/os.py", line 157, in makedirs
    mkdir(name, mode)
OSError: [Errno 13] Permission denied: '/haiwen'