Cannot connect to kernels & terminals error 400

I have setup tljh on ubuntu server 18.04 on a new virtual machine (running on VMWare). There is no https (yet), it is in a local network. No user can connect to terminals nor kernels.

This is the error in the browser for a notebook: Firefox kann keine Verbindung zu dem Server unter ws://<ipaddress>/user/<user>/api/kernels/<token-id>/channels?session_id=<session-id> aufbauen.

same thing for a terminal: Firefox kann keine Verbindung zu dem Server unter ws://<ipaddress>/user/test/terminals/websocket/1 aufbauen.

User logs show 400 GET regarding above-mentioned addresses. I don’t see anything interesting in the jupyterhub logs nor the user logs nor traefik logs. Besides, my “what does the Installer do?” mentions configurable-http-proxy. Well it isn’t present on my install.

This isn’t about tornado as mentioned in https://github.com/jupyterhub/the-littlest-jupyterhub/issues/290 , both “hub” and “user” conda list version 5.1.1. Other similar posts of this error with jupyterhub mentions configuration of Nginx or Apache. What could it be with tljh?

I have done exactly the same install on a VirtualBox VM, and it still works perfectly there. I don’t see any difference in the two installs (both don’t have the configurable-http-proxy service). I installed both following http://tljh.jupyter.org/en/latest/install/custom-server.html to the letter.

[hyamanieu]

@GeorgianaElena FYI I don’t have this issue anymore for the past year. I don’t know what changed since, sorry for not keeping up with this. A ubuntu update? I guess it can be reopened if necessary. Ping to @jdkruzr

[jdkruzr]

@GeorgianaElena FYI I don’t have this issue anymore for the past year. I don’t know what changed since, sorry for not keeping up with this. A ubuntu update? I guess it can be reopened if necessary. Ping to @jdkruzr

Thanks for updating - I haven’t looked at it in quite a while but may dive in again in the coming weeks.