[I 2021-10-12 18:06:11.446 JupyterHub provider:574] Creating oauth client jupyterhub-user-vincenzo
[I 2021-10-12 18:06:11.589 JupyterHub spawner:1483] Spawning jupyterhub-singleuser --port=60621
Traceback (most recent call last):
  File "/usr/local/bin/jupyterhub-singleuser", line 5, in <module>
    from jupyterhub.singleuser import main
  File "/usr/local/lib/python3.8/dist-packages/jupyterhub/singleuser/__init__.py", line 5, in <module>
    from .app import main
  File "/usr/local/lib/python3.8/dist-packages/jupyterhub/singleuser/app.py", line 16, in <module>
    App = import_item(JUPYTERHUB_SINGLEUSER_APP)
  File "/usr/local/lib/python3.8/dist-packages/traitlets/utils/importstring.py", line 30, in import_item
    module = __import__(package, fromlist=[obj])
ModuleNotFoundError: No module named 'notebook'
[I 2021-10-12 18:06:12.380 JupyterHub log:189] 302 GET /hub/spawn/vincenzo -> /hub/spawn-pending/vincenzo (vincenzo@::ffff:151.35.179.254) 1061.31ms
[I 2021-10-12 18:06:12.695 JupyterHub pages:402] vincenzo is pending spawn
ERROR:asyncio:Task exception was never retrieved
future: <Task finished name='Task-401' coro=<BaseHandler.spawn_single_user() done, defined at /usr/local/lib/python3.8/dist-packages/jupyterhub/handlers/base.py:796> exception=HTTPError()>
Traceback (most recent call last):
  File "/usr/local/lib/python3.8/dist-packages/jupyterhub/handlers/base.py", line 996, in spawn_single_user
    await gen.with_timeout(
tornado.util.TimeoutError: Timeout

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.8/dist-packages/jupyterhub/handlers/base.py", line 1030, in spawn_single_user
    raise web.HTTPError(
tornado.web.HTTPError: HTTP 500: Internal Server Error (Spawner failed to start [status=1]. The logs for vincenzo may contain details.)
[W 2021-10-12 18:06:43.316 JupyterHub user:767] vincenzo's server never showed up at http://127.0.0.1:60621/user/vincenzo/ after 30 seconds. Giving up
[E 2021-10-12 18:06:43.489 JupyterHub gen:623] Exception in Future <Task finished name='Task-402' coro=<BaseHandler.spawn_single_user.<locals>.finish_user_spawn() done, defined at /usr/local/lib/python3.8/dist-packages/jupyterhub/handlers/base.py:900> exception=TimeoutError("Server at http://127.0.0.1:60621/user/vincenzo/ didn't respond in 30 seconds")> after timeout
    Traceback (most recent call last):
      File "/usr/local/lib/python3.8/dist-packages/tornado/gen.py", line 618, in error_callback
        future.result()
      File "/usr/local/lib/python3.8/dist-packages/jupyterhub/handlers/base.py", line 907, in finish_user_spawn
        await spawn_future
      File "/usr/local/lib/python3.8/dist-packages/jupyterhub/user.py", line 748, in spawn
        await self._wait_up(spawner)
      File "/usr/local/lib/python3.8/dist-packages/jupyterhub/user.py", line 795, in _wait_up
        raise e
      File "/usr/local/lib/python3.8/dist-packages/jupyterhub/user.py", line 762, in _wait_up
        resp = await server.wait_up(
      File "/usr/local/lib/python3.8/dist-packages/jupyterhub/utils.py", line 236, in wait_for_http_server
        re = await exponential_backoff(
      File "/usr/local/lib/python3.8/dist-packages/jupyterhub/utils.py", line 184, in exponential_backoff
        raise TimeoutError(fail_message)
    TimeoutError: Server at http://127.0.0.1:60621/user/vincenzo/ didn't respond in 30 seconds

[I 2021-10-12 18:06:43.492 JupyterHub log:189] 200 GET /hub/api/users/vincenzo/server/progress (vincenzo@::ffff:151.35.179.254) 30378.69ms