Constant server connection error (404) and notebook saving error (405 method not allowed)

For the past few days jupyter hub has been giving me server connection errors (404 not found), which pop up every 30 seconds or so. In addition, there are an occasional error 405 - method not allowed when jupyter attempts to save the notebook.

These errors appear after perhaps a minute from refreshing the page with a browser. Funny enough, if I can start a notebook/terminal/console immediately after refreshing, I can continue using the system, but any progress will not be saved.

If it helps, once i received an error complaining that jupyter notebook was an older version, but jupyter hub was expecting a newer one. Unfortunately I did not record the version numbers.

Anything I can do about this issue? My colleagues do not seem to be suffering from it, so I wonder if it has something to do with my user account?


this error happens whenever you have a shared-nb notebook open. These files are read only, so if then juypter lab tries to save changes, it gives an error. The issue is might be as well whenever you have the shared-nb directory open in the sidebar.

We shut down your container, could you please try if you can now work without interruptions?
In case you will face the issue again, we will have to investigate further.

Have a great rest of the day!

Hi Alicja,
Thank you, this seems to have solved the problem!

Hi Alicja,
I was a bit too hasty, and this did not fix the issue. I have currently only two kernels running (terminal, one Notebook running R) and the file pane is in the workspace. I still get the 404 server not found, and the 405 appears with notebook which is authored by myself and is located within the workspace folder.

Refreshing the page sometimes gives internal server error (500), but jupyter hub can be restarted via the home page.

" 500 : Internal Server Error

Redirect loop detected. Notebook has jupyterhub version 0.8.1, but the Hub expects 0.9.4. Try installing jupyterhub==0.9.4 in the user environment if you continue to have problems.

You can try restarting your server from the home page."


Hi Marko,

sorry for the super late reply! In the logs of your container it looks, like you were able to work properly yesterday - is that true? @dzelge has restarted your container once again. We so far have no idea, why you have these issues. Please let us know if they occur again.

Best regards!

Hi Alicja,

No problem! The kernel has been working fine, i think. I was able to run commands, develop scripts etc, with the only annoyance being that I could not really use the jupyterhub interface due to the errors. I had to refresh the page every time I needed to open another notebook, or use the file browser.

But it seems to be working fine at the moment after container restart. Thanks! I’ll let you know if there’s any more problems.