nbclient >= 0.7.1 raises ImportError when trying to open a notebook

[Imipenem]

Hey,

when using nbclient >= 0.7.1 I cannot open any notebook cause of getting a 500: INTERNAL SERVER ERROR and the following error message on the command line:

File "/home/myuser/anaconda3/envs/myenv/lib/python3.8/site-packages/nbclient/util.py", line 9, in <module>
        from jupyter_core.utils import ensure_async, run_sync  # noqa: F401
    ImportError: cannot import name 'ensure_async' from 'jupyter_core.utils' (/home/myuser/anaconda3/envs/myenv/lib/python3.8/site-packages/jupyter_core/utils/__init__.py)

Downgrading nbclient to version 7.0.0 fixes the error.

OS: Ubuntu 18.04 LTS; Python 3.8.

[NonContradiction]

Hi--do you mean downgrading to version 0.7.0 ?