Connection to the notebook server cannot be established

FAQ on notebooks
#1

Hello,

I get the same error message for each notebook I open, here is an example with the sandbox notebook:

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[in english] Connection to the notebook server cannot be established. The notebook will continue its attempts. Check your network connection or the settings of the notebook server.

When I close this message, I can read the text from the notebook, edit its cells, however when I try to run a cell, nothing happens:
image

How can it be fixed? Thank you.

FYI: I am using Chrome and I accepted the cookies. I don’t have any problem with my internet connection.

#2

Hello,

I think this is a kernel connectivity issue. Did you try to restart the kernel ? Kernel > Restart

Regards,

#3

I did restart the kernel, I also tried “shutdown” + “reconnect”, refreshing the page, using my phone’s internet connection, and I still have the same problem.

#4

Can you go here : https://mooc-scikit-1.saclay.inria.fr/jhub/user/020445d91f3eab050551b3157ad49cc9/tree#notebooks start a terminal (new > terminal) and type : env | grep USER

This will help me identify your anonymous account.

#5

Ok, this is what I get :

NB_USER=jovyan
JUPYTERHUB_USER=12cad5b2daca59f5ca9d95ae127f2d39
#6

I see a lot of these errors [W 2021-06-04 11:38:12.469 SingleUserNotebookApp zmqhandlers:275] Couldn't authenticate WebSocket connection in your container.
This could be due to a plugin, do you use any ?

#7

Yes, I use several plugins on Chrome. I desactivated all of them and refreshed the page, but I still had the same error.

So I have just installed Firefox, and on this browser I can run cells without any error. Now I can follow the course from there, even though it is not the most convenient for me. :slight_smile:

#8

We are glad you found a way around and are very sorry for the inconvenience caused by this technical problem.

I’ll dig around to find what caused it.

#9

Thank you for your help !