When I am at the: “Turning Your Notebook into a Real App” section,
I uncomment these 2 lines:
!pip install voila
!jupyter serverextension enable voila —sys-prefix
And I get this error (at the very end):
Error loading server extension —sys-prefix
X is —sys-prefix importable?
Am I doing it wrong? The explanation is a bit too terse for me, and any help would be much appreciated 
Here is the full log:
Collecting voila
Downloading voila-0.1.22-py3-none-any.whl (5.9 MB)
|████████████████████████████████| 5.9 MB 5.0 MB/s eta 0:00:01
Requirement already satisfied: pygments<3,>=2.4.1 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from voila) (2.6.1)
Collecting jupyter-server<0.2.0,>=0.1.0
Downloading jupyter_server-0.1.1-py2.py3-none-any.whl (183 kB)
|████████████████████████████████| 183 kB 39.9 MB/s eta 0:00:01
Collecting async-generator
Downloading async_generator-1.10-py3-none-any.whl (18 kB)
Collecting jupyterlab-pygments<0.2,>=0.1.0
Downloading jupyterlab_pygments-0.1.1-py2.py3-none-any.whl (4.6 kB)
Requirement already satisfied: nbconvert<6,>=5.5.0 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from voila) (5.6.1)
Requirement already satisfied: prometheus-client in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jupyter-server<0.2.0,>=0.1.0->voila) (0.8.0)
Requirement already satisfied: terminado>=0.8.1 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jupyter-server<0.2.0,>=0.1.0->voila) (0.8.3)
Requirement already satisfied: nbformat in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jupyter-server<0.2.0,>=0.1.0->voila) (5.0.7)
Requirement already satisfied: ipykernel in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jupyter-server<0.2.0,>=0.1.0->voila) (5.3.4)
Requirement already satisfied: jupyter-client>=5.3.1 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jupyter-server<0.2.0,>=0.1.0->voila) (6.1.6)
Requirement already satisfied: ipython-genutils in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jupyter-server<0.2.0,>=0.1.0->voila) (0.2.0)
Requirement already satisfied: tornado>=4 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jupyter-server<0.2.0,>=0.1.0->voila) (6.0.4)
Requirement already satisfied: traitlets>=4.2.1 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jupyter-server<0.2.0,>=0.1.0->voila) (4.3.3)
Requirement already satisfied: pyzmq>=17 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jupyter-server<0.2.0,>=0.1.0->voila) (19.0.2)
Requirement already satisfied: jupyter-core>=4.4.0 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jupyter-server<0.2.0,>=0.1.0->voila) (4.6.3)
Requirement already satisfied: jinja2 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jupyter-server<0.2.0,>=0.1.0->voila) (2.11.2)
Requirement already satisfied: Send2Trash in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jupyter-server<0.2.0,>=0.1.0->voila) (1.5.0)
Requirement already satisfied: bleach in /opt/conda/envs/fastai/lib/python3.8/site-packages (from nbconvert<6,>=5.5.0->voila) (3.1.5)
Requirement already satisfied: mistune<2,>=0.8.1 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from nbconvert<6,>=5.5.0->voila) (0.8.4)
Requirement already satisfied: defusedxml in /opt/conda/envs/fastai/lib/python3.8/site-packages (from nbconvert<6,>=5.5.0->voila) (0.6.0)
Requirement already satisfied: pandocfilters>=1.4.1 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from nbconvert<6,>=5.5.0->voila) (1.4.2)
Requirement already satisfied: testpath in /opt/conda/envs/fastai/lib/python3.8/site-packages (from nbconvert<6,>=5.5.0->voila) (0.4.4)
Requirement already satisfied: entrypoints>=0.2.2 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from nbconvert<6,>=5.5.0->voila) (0.3)
Requirement already satisfied: jsonschema!=2.5.0,>=2.4 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from nbformat->jupyter-server<0.2.0,>=0.1.0->voila) (3.2.0)
Requirement already satisfied: ipython>=5.0.0 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from ipykernel->jupyter-server<0.2.0,>=0.1.0->voila) (7.17.0)
Requirement already satisfied: python-dateutil>=2.1 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jupyter-client>=5.3.1->jupyter-server<0.2.0,>=0.1.0->voila) (2.8.1)
Requirement already satisfied: six in /opt/conda/envs/fastai/lib/python3.8/site-packages (from traitlets>=4.2.1->jupyter-server<0.2.0,>=0.1.0->voila) (1.15.0)
Requirement already satisfied: decorator in /opt/conda/envs/fastai/lib/python3.8/site-packages (from traitlets>=4.2.1->jupyter-server<0.2.0,>=0.1.0->voila) (4.4.2)
Requirement already satisfied: MarkupSafe>=0.23 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jinja2->jupyter-server<0.2.0,>=0.1.0->voila) (1.1.1)
Requirement already satisfied: packaging in /opt/conda/envs/fastai/lib/python3.8/site-packages (from bleach->nbconvert<6,>=5.5.0->voila) (20.4)
Requirement already satisfied: webencodings in /opt/conda/envs/fastai/lib/python3.8/site-packages (from bleach->nbconvert<6,>=5.5.0->voila) (0.5.1)
Requirement already satisfied: attrs>=17.4.0 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jsonschema!=2.5.0,>=2.4->nbformat->jupyter-server<0.2.0,>=0.1.0->voila) (20.1.0)
Requirement already satisfied: pyrsistent>=0.14.0 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jsonschema!=2.5.0,>=2.4->nbformat->jupyter-server<0.2.0,>=0.1.0->voila) (0.16.0)
Requirement already satisfied: setuptools in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jsonschema!=2.5.0,>=2.4->nbformat->jupyter-server<0.2.0,>=0.1.0->voila) (49.6.0.post20200814)
Requirement already satisfied: pickleshare in /opt/conda/envs/fastai/lib/python3.8/site-packages (from ipython>=5.0.0->ipykernel->jupyter-server<0.2.0,>=0.1.0->voila) (0.7.5)
Requirement already satisfied: backcall in /opt/conda/envs/fastai/lib/python3.8/site-packages (from ipython>=5.0.0->ipykernel->jupyter-server<0.2.0,>=0.1.0->voila) (0.2.0)
Requirement already satisfied: jedi>=0.10 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from ipython>=5.0.0->ipykernel->jupyter-server<0.2.0,>=0.1.0->voila) (0.17.2)
Requirement already satisfied: pexpect; sys_platform != “win32” in /opt/conda/envs/fastai/lib/python3.8/site-packages (from ipython>=5.0.0->ipykernel->jupyter-server<0.2.0,>=0.1.0->voila) (4.8.0)
Requirement already satisfied: prompt-toolkit!=3.0.0,!=3.0.1,<3.1.0,>=2.0.0 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from ipython>=5.0.0->ipykernel->jupyter-server<0.2.0,>=0.1.0->voila) (3.0.6)
Requirement already satisfied: pyparsing>=2.0.2 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from packaging->bleach->nbconvert<6,>=5.5.0->voila) (2.4.7)
Requirement already satisfied: parso<0.8.0,>=0.7.0 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from jedi>=0.10->ipython>=5.0.0->ipykernel->jupyter-server<0.2.0,>=0.1.0->voila) (0.7.1)
Requirement already satisfied: ptyprocess>=0.5 in /opt/conda/envs/fastai/lib/python3.8/site-packages (from pexpect; sys_platform != “win32”->ipython>=5.0.0->ipykernel->jupyter-server<0.2.0,>=0.1.0->voila) (0.6.0)
Requirement already satisfied: wcwidth in /opt/conda/envs/fastai/lib/python3.8/site-packages (from prompt-toolkit!=3.0.0,!=3.0.1,<3.1.0,>=2.0.0->ipython>=5.0.0->ipykernel->jupyter-server<0.2.0,>=0.1.0->voila) (0.2.5)
Installing collected packages: jupyter-server, async-generator, jupyterlab-pygments, voila
Successfully installed async-generator-1.10 jupyter-server-0.1.1 jupyterlab-pygments-0.1.1 voila-0.1.22
Enabling: voila
- Writing config: /root/.jupyter
- Validating…
voila 0.1.22 OK
Enabling: —sys-prefix
- Validating…
- Writing config: /root/.jupyter
- Validating…
Error loading server extension —sys-prefix
X is —sys-prefix importable?
- Validating…