Pytyon: Jupyter lab 起動時に cannot import name 'soft_unicode' from 'markupsafe'

C:\Users\Masahiro\Downloads\slack>jupyter lab
Traceback (most recent call last):
  File "c:\users\masahiro\appdata\local\programs\python\python37\lib\runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "c:\users\masahiro\appdata\local\programs\python\python37\lib\runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "C:\Users\Masahiro\AppData\Local\Programs\Python\Python37\Scripts\jupyter-lab.EXE\__main__.py", line 4, in <module>
  File "c:\users\masahiro\appdata\local\programs\python\python37\lib\site-packages\jupyterlab\__init__.py", line 7, in <module>
    from .labapp import LabApp
  File "c:\users\masahiro\appdata\local\programs\python\python37\lib\site-packages\jupyterlab\labapp.py", line 12, in <module>
    from jinja2 import Environment, FileSystemLoader
  File "c:\users\masahiro\appdata\local\programs\python\python37\lib\site-packages\jinja2\__init__.py", line 12, in <module>
    from .environment import Environment
  File "c:\users\masahiro\appdata\local\programs\python\python37\lib\site-packages\jinja2\environment.py", line 25, in <module>
    from .defaults import BLOCK_END_STRING
  File "c:\users\masahiro\appdata\local\programs\python\python37\lib\site-packages\jinja2\defaults.py", line 3, in <module>
    from .filters import FILTERS as DEFAULT_FILTERS  # noqa: F401
  File "c:\users\masahiro\appdata\local\programs\python\python37\lib\site-packages\jinja2\filters.py", line 13, in <module>
    from markupsafe import soft_unicode
ImportError: cannot import name 'soft_unicode' from 'markupsafe' (c:\users\masahiro\appdata\local\programs\python\python37\lib\site-packages\markupsafe\__init__.py)

qiita.com

を参考に、pip install Flask で解決した。