python安装jupyter报错?报错

Traceback (most recent call last):
  File "C:\Python27\lib\runpy.py", line 174, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "C:\Python27\lib\runpy.py", line 72, in _run_code
    exec code in run_globals
  File "C:\Python27\Scripts\pip.exe\__main__.py", line 5, in <module>
  File "C:\Python27\lib\site-packages\pip\_internal\__init__.py", line 5, in <mo
dule>
    import logging
  File "C:\Python27\lib\logging\__init__.py", line 26, in <module>
    import sys, os, time, cStringIO, traceback, warnings, weakref, collections
  File "C:\Python27\lib\weakref.py", line 14, in <module>
    from _weakref import (
ImportError: cannot import name _remove_dead_weakref、

我这是2.7的python