Jupyterhub Error 503: Proxy Target Missing

Question

I managed to establish Jupyterhub on my server and it worked well. Since I tried to restart the Jupyterhub service it doesn't work any more and when I'm trying to run it I see the error message:

Proxy appears to be running at http://*:8000/, but I can't access it (HTTP 403: Forbidden)
Did CONFIGPROXY_AUTH_TOKEN change?

In the web browser I get

Error 503: Proxy Target Missing. 

It may be connected to the warning that I see every time when I run Jupyterhub :

Generating CONFIGPROXY_AUTH_TOKEN. Restarting the Hub will require restarting the proxy.
Set CONFIGPROXY_AUTH_TOKEN env or JupyterHub.proxy_auth_token config to avoid this message.

Answer 1

sudo pkill node

Will kill the proxy service.

Restarting Jupyterhub will restart it.

For Ubuntu 14.04

jupyterhub --no-ssl &

no ssl if you don't have ssl certificates setup & or ampersand to keep the service running when your tty or terminal session closes

You can use sudo pkill jupyterhub to kill the process. (not always as reliable as creating a init service)

Answer 2

You don't have to restart the entire machine, killing configurable-http-proxy process before restarting jupyterhub should be enough:

[root@box jupyterhub]# ps aux | grep proxy 
jupyrhub 42079 0.0  0.1 741424 20248 ?        Sl   15:10   0:00 node /usr/bin/configurable-http-proxy --ip  --port 9876 --api-ip 127.0.0.1
--api-port 9877 --default-target http://127.0.0.1:8081 --ssl-key /etc/pki/tls/private/server_AZL-BUEdge-01.key --ssl-cert
/etc/pki/tls/private/server_AZL-BUEdge-01_fullchain.pem root     42683
0.0  0.0 103308   864 pts/10   S+   15:20   0:00 grep proxy 
[root@box]# kill -9 42079