# 500 server error: Failed to connect to Hub API at '\<hostIP:8081\>/hub/api'. Is the Hub accessible at this URL (from host: 610895540bb5)? 

**URL:** <https://discourse.jupyter.org/t/500-server-error-failed-to-connect-to-hub-api-at-hostip-8081-hub-api-is-the-hub-accessible-at-this-url-from-host-610895540bb5/3614>\
**Category:** General\
**Tags:** how-to\
**Created:** [March 13, 2020, 4:26pm UTC](https://discourse.jupyter.org/t/500-server-error-failed-to-connect-to-hub-api-at-hostip-8081-hub-api-is-the-hub-accessible-at-this-url-from-host-610895540bb5/3614 "2020-03-13T16:26:02Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![nwong44](https://avatars.discourse-cdn.com/v4/letter/n/b2d939/32.png) [@nwong44](https://discourse.jupyter.org/u/nwong44)\
**Post date:** [March 13, 2020, 4:26pm UTC](https://discourse.jupyter.org/t/500-server-error-failed-to-connect-to-hub-api-at-hostip-8081-hub-api-is-the-hub-accessible-at-this-url-from-host-610895540bb5/3614/1 "2020-03-13T16:26:02Z")

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Hi, I’ve been having this error. When I go to the URL, it displays the version of Jupyterhub.

I have tried using this command “sudo ufw allow in on docker0 to any port 8081”  
Also, here are my configs:  
c.JupyterHub.spawner\_class = ‘dockerspawner.DockerSpawner’

c.DockerSpawner.image = ‘jupyter/scipy-notebook’  
c.DockerSpawner.hub\_ip\_connect = ‘’  
c.JupyterHub.hub\_ip = ‘’  
#c.JupyterHub.hub\_ip = ‘0.0.0.0’  
c.JupyterHub.port = 8000

I have also configured proxy in the docker http.conf file as well.

Thanks!