Notebook: Dead Jupyter Kernel with python3

[jcgarciaca]

I am trying to use jupyter notebook with python3. Then I added the kernel with

python3 -m pip install ipykernel
python3 -m ipykernel install --user

But when I start a notebook it shows a Dead kernel message, and the terminal shows

Fatal Python error: Py_Initialize: Unable to get the locale encoding
ImportError: No module named 'encodings'

If I choose python2 kernel it works well. I can run python command in console without any issue.

[takluyver]

How are you launching the notebook, and how did you install python3? I think that error must mean there's something wrong in the environment - it's an error that Python gives before it runs any of our code.

[jcgarciaca]

Hi @takluyver.
I just run the notebook with jupyter notebook (or jupyter-notebook, both have same result) and I installed python3 with sudo apt-get. But I get this error only with the notebook and python3 kernel. Actually, I am able to run python3 commands in console, as well as my scripts and they work well. I do:

$ python3
Python 3.4.2 (default, Oct  8 2014, 10:45:20) 
[GCC 4.9.1] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import numpy as np
>>> 

I also checked the notebook with python2 and works properly.

According with some posts I verified the kernelspecs such I get

"python3": {
  "resource_dir": "/usr/local/share/jupyter/kernels/python3", 
  "spec": {
    "interrupt_mode": "signal", 
    "display_name": "Python 3", 
    "env": {}, 
    "language": "python", 
    "argv": [
      "/usr/bin/python3", 
      "-m", 
      "ipykernel_launcher", 
      "-f", 
      "{connection_file}"
    ], 
    "metadata": {}
  }
}, 
"python2": {
  "resource_dir": "/opt/bitnami/python/share/jupyter/kernels/python2", 
  "spec": {
    "interrupt_mode": "signal", 
    "display_name": "Python 2", 
    "env": {}, 
    "language": "python", 
    "argv": [
      "python", 
      "-m", 
      "ipykernel_launcher", 
      "-f", 
      "{connection_file}"
    ], 
    "metadata": {}
  }
}

I am not sure what is the issue here.
Does it depend on PYTHONPATH or PYTHONHOME? When I use echo for them, both are empty

[takluyver]

No, it shouldn't require PYTHONPATH or PYTHONHOME to be set.

What happens if you install the notebook with Python 3 (python3 -m pip install notebook) and launch a Python 3 kernel from a Python 3 server?

[jcgarciaca]

If I run python3 -m pip install notebook it shows requirement already satisfied as follow

Requirement already satisfied: notebook in /usr/local/lib/python3.4/dist-packages
Requirement already satisfied: terminado>=0.8.1 in /usr/local/lib/python3.4/dist-packages (from notebook)
Requirement already satisfied: jupyter-client>=5.2.0 in /usr/local/lib/python3.4/dist-packages (from notebook)
Requirement already satisfied: tornado>=4 in /usr/local/lib/python3.4/dist-packages (from notebook)
Requirement already satisfied: Send2Trash in /usr/local/lib/python3.4/dist-packages (from notebook)
Requirement already satisfied: ipython-genutils in /usr/local/lib/python3.4/dist-packages (from notebook)
Requirement already satisfied: ipykernel in /usr/local/lib/python3.4/dist-packages (from notebook)
Requirement already satisfied: jupyter-core>=4.4.0 in /usr/local/lib/python3.4/dist-packages (from notebook)
Requirement already satisfied: nbformat in /usr/local/lib/python3.4/dist-packages (from notebook)
Requirement already satisfied: jinja2 in /usr/local/lib/python3.4/dist-packages (from notebook)
Requirement already satisfied: nbconvert in /usr/local/lib/python3.4/dist-packages (from notebook)
Requirement already satisfied: traitlets>=4.2.1 in /usr/local/lib/python3.4/dist-packages (from notebook)
Requirement already satisfied: ptyprocess; os_name != "nt" in /usr/local/lib/python3.4/dist-packages (from terminado>=0.8.1->notebook)
Requirement already satisfied: python-dateutil>=2.1 in /usr/local/lib/python3.4/dist-packages (from jupyter-client>=5.2.0->notebook)
Requirement already satisfied: pyzmq>=13 in /usr/local/lib/python3.4/dist-packages (from jupyter-client>=5.2.0->notebook)
Requirement already satisfied: backports_abc>=0.4 in /usr/local/lib/python3.4/dist-packages (from tornado>=4->no
tebook)
Requirement already satisfied: ipython>=4.0.0 in /usr/local/lib/python3.4/dist-packages (from ipykernel->noteboo
k)
Requirement already satisfied: jsonschema!=2.5.0,>=2.4 in /usr/local/lib/python3.4/dist-packages (from nbformat-
>notebook)
Requirement already satisfied: MarkupSafe>=0.23 in /usr/local/lib/python3.4/dist-packages (from jinja2->notebook
)
Requirement already satisfied: entrypoints>=0.2.2 in /usr/local/lib/python3.4/dist-packages (from nbconvert->not
ebook)
Requirement already satisfied: pandocfilters>=1.4.1 in /usr/local/lib/python3.4/dist-packages (from nbconvert->n
otebook)
Requirement already satisfied: testpath in /usr/local/lib/python3.4/dist-packages (from nbconvert->notebook)
Requirement already satisfied: bleach in /usr/local/lib/python3.4/dist-packages (from nbconvert->notebook)
Requirement already satisfied: pygments in /usr/local/lib/python3.4/dist-packages (from nbconvert->notebook)
Requirement already satisfied: mistune>=0.7.4 in /usr/local/lib/python3.4/dist-packages (from nbconvert->noteboo
k)
Requirement already satisfied: six in /usr/local/lib/python3.4/dist-packages (from traitlets>=4.2.1->notebook)
Requirement already satisfied: decorator in /usr/local/lib/python3.4/dist-packages (from traitlets>=4.2.1->noteb
ook)
Requirement already satisfied: pickleshare in /usr/local/lib/python3.4/dist-packages (from ipython>=4.0.0->ipyke
rnel->notebook)
Requirement already satisfied: typing; python_version <= "3.4" in /usr/local/lib/python3.4/dist-packages (from i
python>=4.0.0->ipykernel->notebook)
Requirement already satisfied: setuptools>=18.5 in /usr/local/lib/python3.4/dist-packages (from ipython>=4.0.0->
ipykernel->notebook)
Requirement already satisfied: simplegeneric>0.8 in /usr/local/lib/python3.4/dist-packages (from ipython>=4.0.0-
>ipykernel->notebook)
Requirement already satisfied: pexpect; sys_platform != "win32" in /usr/local/lib/python3.4/dist-packages (from 
ipython>=4.0.0->ipykernel->notebook)
Requirement already satisfied: jedi>=0.10 in /usr/local/lib/python3.4/dist-packages (from ipython>=4.0.0->ipyker
nel->notebook)
Requirement already satisfied: prompt-toolkit<2.0.0,>=1.0.4 in /usr/local/lib/python3.4/dist-packages (from ipyt
hon>=4.0.0->ipykernel->notebook)
Requirement already satisfied: html5lib!=1.0b1,!=1.0b2,!=1.0b3,!=1.0b4,!=1.0b5,!=1.0b6,!=1.0b7,!=1.0b8,>=0.99999
999pre in /usr/local/lib/python3.4/dist-packages (from bleach->nbconvert->notebook)
Requirement already satisfied: parso==0.1.1 in /usr/local/lib/python3.4/dist-packages (from jedi>=0.10->ipython>
=4.0.0->ipykernel->notebook)
Requirement already satisfied: wcwidth in /usr/local/lib/python3.4/dist-packages (from prompt-toolkit<2.0.0,>=1.
0.4->ipython>=4.0.0->ipykernel->notebook)
Requirement already satisfied: webencodings in /usr/local/lib/python3.4/dist-packages (from html5lib!=1.0b1,!=1.
0b2,!=1.0b3,!=1.0b4,!=1.0b5,!=1.0b6,!=1.0b7,!=1.0b8,>=0.99999999pre->bleach->nbconvert->notebook)

How do I launch a Python 3 kernel from a Python 3 server?

[OrangeBot]

How do I launch a Python 3 kernel from a Python 3 server?

You need to launch jupyter that is in your python3 directory.
Something like that: /usr/local/lib/python3.4/bin/jupyter notebook

[jcgarciaca]

@OrangeBot,
My /usr/local/lib/python3.4 doesn't have bin directory, it only has dist-packages. Is it ok?
Here, I do python3 /usr/local/lib/python3.4/dist-packages/jupyter.py but it shows jupyter.py: error: one of the arguments --version subcommand --config-dir --data-dir --runtime-dir --paths is required. Which path should I define?
I tried --paths=/home/jcgarciaca/models/research/object_detection and --paths=/home/jcgarciaca/models/research/object_detection/object_detection_tutorial.ipynb but they show jupyter.py: error: argument --paths: ignored explicit argument '/home/jcgarciaca/models/research/object_detection'.

[takluyver]

Yes, the bin folder will be /usr/local/bin and it's shared between Python 2 and 3 (and all sorts of other things). You can launch the notebook with a specific python version by running python3 -m notebook

[jcgarciaca]

Thank you @takluyver, with python3 -m notebook I am able to run my notebook perfectly with python3

[takluyver]

OK, that's good. I'm still puzzled why it had the problem with encodings when you launched it with Python 2, though.

[yishanchuan]

My host is in Ubuntu 18.04, Python 3.6.6. Then, I use pip3 install --user notebook to solve the problem. The key lost wheel is prompt_toolkit-2.0.6-py3-none-any.whl.
The installation requirement is `pip3 install --user notebook

Collecting notebook
Using cached https://files.pythonhosted.org/packages/44/16/9f108b675828c4117cfe72d8d0f97094163c40584e40c46ec48a1e862693/notebook-5.7.0-py2.py3-none-any.whl
Collecting nbconvert (from notebook)
Using cached https://files.pythonhosted.org/packages/b5/bb/94c493051d60e5b9c0f7f9a368b324201818c1b1c4cae85d1e49a41846c7/nbconvert-5.4.0-py2.py3-none-any.whl
Collecting pyzmq>=17 (from notebook)
Using cached https://files.pythonhosted.org/packages/48/93/59592cb294761aaa40589b544eaa5175446d687ff95beeeb666de60f3274/pyzmq-17.1.2-cp36-cp36m-manylinux1_x86_64.whl
Collecting nbformat (from notebook)
Using cached https://files.pythonhosted.org/packages/da/27/9a654d2b6cc1eaa517d1c5a4405166c7f6d72f04f6e7eea41855fe808a46/nbformat-4.4.0-py2.py3-none-any.whl
Collecting jinja2 (from notebook)
Using cached https://files.pythonhosted.org/packages/7f/ff/ae64bacdfc95f27a016a7bed8e8686763ba4d277a78ca76f32659220a731/Jinja2-2.10-py2.py3-none-any.whl
Collecting prometheus-client (from notebook)
Collecting terminado>=0.8.1 (from notebook)
Using cached https://files.pythonhosted.org/packages/2e/20/a26211a24425923d46e1213b376a6ee60dc30bcdf1b0c345e2c3769deb1c/terminado-0.8.1-py2.py3-none-any.whl
Collecting jupyter-core>=4.4.0 (from notebook)
Using cached https://files.pythonhosted.org/packages/1d/44/065d2d7bae7bebc06f1dd70d23c36da8c50c0f08b4236716743d706762a8/jupyter_core-4.4.0-py2.py3-none-any.whl
Collecting jupyter-client>=5.2.0 (from notebook)
Using cached https://files.pythonhosted.org/packages/94/dd/fe6c4d683b09eb05342bd2816b7779663f71762b4fa9c2d5203d35d17354/jupyter_client-5.2.3-py2.py3-none-any.whl
Collecting ipython-genutils (from notebook)
Using cached https://files.pythonhosted.org/packages/fa/bc/9bd3b5c2b4774d5f33b2d544f1460be9df7df2fe42f352135381c347c69a/ipython_genutils-0.2.0-py2.py3-none-any.whl
Collecting Send2Trash (from notebook)
Using cached https://files.pythonhosted.org/packages/49/46/c3dc27481d1cc57b9385aff41c474ceb7714f7935b1247194adae45db714/Send2Trash-1.5.0-py3-none-any.whl
Collecting traitlets>=4.2.1 (from notebook)
Using cached https://files.pythonhosted.org/packages/93/d6/abcb22de61d78e2fc3959c964628a5771e47e7cc60d53e9342e21ed6cc9a/traitlets-4.3.2-py2.py3-none-any.whl
Collecting ipykernel (from notebook)
Using cached https://files.pythonhosted.org/packages/d8/b0/f0be5c5ab335196f5cce96e5b889a4fcf5bfe462eb0acc05cd7e2caf65eb/ipykernel-5.1.0-py3-none-any.whl
Collecting tornado>=4 (from notebook)
Collecting pandocfilters>=1.4.1 (from nbconvert->notebook)
Collecting defusedxml (from nbconvert->notebook)
Using cached https://files.pythonhosted.org/packages/87/1c/17f3e3935a913dfe2a5ca85fa5ccbef366bfd82eb318b1f75dadbf0affca/defusedxml-0.5.0-py2.py3-none-any.whl
Collecting bleach (from nbconvert->notebook)
Using cached https://files.pythonhosted.org/packages/d4/0d/4696373c3b714f6022d668fbab619690a42050dbeacede6d10ed97fbd3e2/bleach-3.0.2-py2.py3-none-any.whl
Collecting testpath (from nbconvert->notebook)
Using cached https://files.pythonhosted.org/packages/be/a4/162f9ebb6489421fe46dcca2ae420369edfee4b563c668d93cb4605d12ba/testpath-0.4.2-py2.py3-none-any.whl
Collecting mistune>=0.8.1 (from nbconvert->notebook)
Using cached https://files.pythonhosted.org/packages/09/ec/4b43dae793655b7d8a25f76119624350b4d65eb663459eb9603d7f1f0345/mistune-0.8.4-py2.py3-none-any.whl
Collecting pygments (from nbconvert->notebook)
Using cached https://files.pythonhosted.org/packages/02/ee/b6e02dc6529e82b75bb06823ff7d005b141037cb1416b10c6f00fc419dca/Pygments-2.2.0-py2.py3-none-any.whl
Collecting entrypoints>=0.2.2 (from nbconvert->notebook)
Using cached https://files.pythonhosted.org/packages/cc/8b/4eefa9b47f1910b3d2081da67726b066e379b04ca897acfe9f92bac56147/entrypoints-0.2.3-py2.py3-none-any.whl
Collecting jsonschema!=2.5.0,>=2.4 (from nbformat->notebook)
Using cached https://files.pythonhosted.org/packages/77/de/47e35a97b2b05c2fadbec67d44cfcdcd09b8086951b331d82de90d2912da/jsonschema-2.6.0-py2.py3-none-any.whl
Collecting MarkupSafe>=0.23 (from jinja2->notebook)
Collecting ptyprocess; os_name != "nt" (from terminado>=0.8.1->notebook)
Using cached https://files.pythonhosted.org/packages/d1/29/605c2cc68a9992d18dada28206eeada56ea4bd07a239669da41674648b6f/ptyprocess-0.6.0-py2.py3-none-any.whl
Collecting python-dateutil>=2.1 (from jupyter-client>=5.2.0->notebook)
Using cached https://files.pythonhosted.org/packages/cf/f5/af2b09c957ace60dcfac112b669c45c8c97e32f94aa8b56da4c6d1682825/python_dateutil-2.7.3-py2.py3-none-any.whl
Collecting six (from traitlets>=4.2.1->notebook)
Using cached https://files.pythonhosted.org/packages/67/4b/141a581104b1f6397bfa78ac9d43d8ad29a7ca43ea90a2d863fe3056e86a/six-1.11.0-py2.py3-none-any.whl
Collecting decorator (from traitlets>=4.2.1->notebook)
Using cached https://files.pythonhosted.org/packages/bc/bb/a24838832ba35baf52f32ab1a49b906b5f82fb7c76b2f6a7e35e140bac30/decorator-4.3.0-py2.py3-none-any.whl
Collecting ipython>=5.0.0 (from ipykernel->notebook)
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Collecting webencodings (from bleach->nbconvert->notebook)
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Collecting pickleshare (from ipython>=5.0.0->ipykernel->notebook)
Using cached https://files.pythonhosted.org/packages/9a/41/220f49aaea88bc6fa6cba8d05ecf24676326156c23b991e80b3f2fc24c77/pickleshare-0.7.5-py2.py3-none-any.whl
Collecting setuptools>=18.5 (from ipython>=5.0.0->ipykernel->notebook)
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Collecting prompt-toolkit<2.1.0,>=2.0.0 (from ipython>=5.0.0->ipykernel->notebook)
Downloading https://files.pythonhosted.org/packages/06/6f/03f10d2206e34a81934b10fb43975a29028e0fe2ae330f9f000bbc0780b7/prompt_toolkit-2.0.6-py3-none-any.whl (336kB)
100% |████████████████████████████████| 337kB 25kB/s
Collecting simplegeneric>0.8 (from ipython>=5.0.0->ipykernel->notebook)
Collecting pexpect; sys_platform != "win32" (from ipython>=5.0.0->ipykernel->notebook)
Using cached https://files.pythonhosted.org/packages/89/e6/b5a1de8b0cc4e07ca1b305a4fcc3f9806025c1b651ea302646341222f88b/pexpect-4.6.0-py2.py3-none-any.whl
Collecting jedi>=0.10 (from ipython>=5.0.0->ipykernel->notebook)
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Collecting backcall (from ipython>=5.0.0->ipykernel->notebook)
Collecting wcwidth (from prompt-toolkit<2.1.0,>=2.0.0->ipython>=5.0.0->ipykernel->notebook)
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Collecting parso>=0.3.0 (from jedi>=0.10->ipython>=5.0.0->ipykernel->notebook)
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Installing collected packages: ipython-genutils, six, decorator, traitlets, jupyter-core, pandocfilters, MarkupSafe, jinja2, defusedxml, webencodings, bleach, jsonschema, nbformat, testpath, mistune, pygments, entrypoints, nbconvert, pyzmq, prometheus-client, ptyprocess, tornado, terminado, python-dateutil, jupyter-client, Send2Trash, pickleshare, setuptools, wcwidth, prompt-toolkit, simplegeneric, pexpect, parso, jedi, backcall, ipython, ipykernel, notebook
Successfully installed MarkupSafe-1.0 Send2Trash-1.5.0 backcall-0.1.0 bleach-3.0.2 decorator-4.3.0 defusedxml-0.5.0 entrypoints-0.2.3 ipykernel-5.1.0 ipython-7.0.1 ipython-genutils-0.2.0 jedi-0.13.1 jinja2-2.10 jsonschema-2.6.0 jupyter-client-5.2.3 jupyter-core-4.4.0 mistune-0.8.4 nbconvert-5.4.0 nbformat-4.4.0 notebook-5.7.0 pandocfilters-1.4.2 parso-0.3.1 pexpect-4.6.0 pickleshare-0.7.5 prometheus-client-0.4.2 prompt-toolkit-2.0.6 ptyprocess-0.6.0 pygments-2.2.0 python-dateutil-2.7.3 pyzmq-17.1.2 setuptools-40.4.3 simplegeneric-0.8.1 six-1.11.0 terminado-0.8.1 testpath-0.4.2 tornado-5.1.1 traitlets-4.3.2 wcwidth-0.1.7 webencodings-0.5.1
`