This document is under active development.

When troubleshooting, you may see unexpected behaviors or receive an error message. These two lists provide links to identifying the cause of the problem and how to resolve it.

JupyterHub proxy fails to start

If you have tried to start the JupyterHub proxy and it fails to start:

  • check if the JupyterHub IP configuration setting is c.JupyterHub.ip = '*'; if it is, try c.JupyterHub.ip = ''
  • Try starting with jupyterhub --ip=

500 error after spawning my single-user server

You receive a 500 error when accessing the URL /user/you/.... This is often seen when your single-user server cannot check your cookies with the Hub.

There are two likely reasons for this:

  1. The single-user server cannot connect to the Hub’s API (networking configuration problems)
  2. The single-user server cannot authenticate its requests (invalid token)


The main symptom is a failure to load any page served by the single-user server, met with a 500 error. This is typically the first page at /user/you after logging in or clicking “Start my server”. When a single-user server receives a request, it makes an API request to the Hub to check if the cookie corresponds to the right user. This request is logged.

If everything is working, it will look like this:

200 GET /hub/api/authorizations/cookie/jupyter-hub-token-name/[secret] (@ 6.10ms

You should see a similar 200 message, as above, in the Hub log when you first visit your single-user server. If you don’t see this message in the log, it may mean that your single-user server isn’t connecting to your Hub.

If you see 403 (forbidden) like this, it’s a token problem:

403 GET /hub/api/authorizations/cookie/jupyter-hub-token-name/[secret] (@ 4.14ms

Check the logs of the single-user server, which may have more detailed information on the cause.

Causes and resolutions:

No authorization request

If you make an API request and it is not received by the server, you likely have a network configuration issue. Often, this happens when the Hub is only listening on (default) and the single-user servers are not on the same ‘machine’ (can be physically remote, or in a docker container or VM). The fix for this case is to make sure that c.JupyterHub.hub_ip is an address that all single-user servers can connect to, e.g.:

c.JupyterHub.hub_ip = ''