Jupyter notebook dead kernel

Question

So I tried to fix my Jupyter notebook (it wasn't letting me import libraries), however, it appears I made things worse. Now whenever I start the notebook, the kernel starts, and then instantly dies. The error I get is below:

[I 15:00:39.002 NotebookApp] Serving notebooks from local directory: /Users/stephanng/Documents/Coding/IPyNB
[I 15:00:39.002 NotebookApp] 0 active kernels 
[I 15:00:39.003 NotebookApp] The Jupyter Notebook is running at: http://localhost:8888/
[I 15:00:39.003 NotebookApp] Use Control-C to stop this server and shut down all kernels (twice to skip confirmation).
[W 15:00:43.558 NotebookApp] Notebook 157 Muon Analysis - Copy.ipynb is not trusted
[I 15:00:44.045 NotebookApp] Kernel started: 152a55a1-e393-4e86-b271-859b924e6a3e
/Users/stephanng/anaconda/envs/py27/bin/python: No module named _signatures; 'ipykernel' is a package and cannot be directly executed
[I 15:00:47.047 NotebookApp] KernelRestarter: restarting kernel (1/5)
/Users/stephanng/anaconda/envs/py27/bin/python: No module named _signatures; 'ipykernel' is a package and cannot be directly executed
[I 15:00:50.059 NotebookApp] KernelRestarter: restarting kernel (2/5)
/Users/stephanng/anaconda/envs/py27/bin/python: No module named _signatures; 'ipykernel' is a package and cannot be directly executed
[I 15:00:53.067 NotebookApp] KernelRestarter: restarting kernel (3/5)
/Users/stephanng/anaconda/envs/py27/bin/python: No module named _signatures; 'ipykernel' is a package and cannot be directly executed
[W 15:00:54.257 NotebookApp] Timeout waiting for kernel_info reply from 152a55a1-e393-4e86-b271-859b924e6a3e
[I 15:00:56.078 NotebookApp] KernelRestarter: restarting kernel (4/5)
WARNING:root:kernel 152a55a1-e393-4e86-b271-859b924e6a3e restarted
/Users/stephanng/anaconda/envs/py27/bin/python: No module named _signatures; 'ipykernel' is a package and cannot be directly executed
[W 15:00:59.094 NotebookApp] KernelRestarter: restart failed
[W 15:00:59.095 NotebookApp] Kernel 152a55a1-e393-4e86-b271-859b924e6a3e died, removing from map.
ERROR:root:kernel 152a55a1-e393-4e86-b271-859b924e6a3e restarted failed!
[W 15:00:59.116 NotebookApp] Kernel deleted before session
[W 15:00:59.117 NotebookApp] 410 DELETE /api/sessions/15eb80b6-d134-4142-96fa-1b1012be280c (::1) 5.42ms referer=http://localhost:8888/notebooks/157%20Muon%20Analysis%20-%20Copy.ipynb

Is there a way to fix this? Or should I just go about a full uninstall and reinstall? Also, how do I go about doing so? When I do sudo pip uninstall jupyter, it doesn't seem to work.

Answer 1

This is a FAQ.

tl;dr: Do this within your notebook if you need e.g. numpy:

import sys
!conda install --yes --prefix {sys.prefix} numpy

Please refer to http://jakevdp.github.io/blog/2017/12/05/installing-python-packages-from-jupyter/ for a detailed discussion of why "import foo" in a Jupyter environment differs from "import foo" in a command line environment.