First time running, got HTTP 599 error

Hi all,

I need some guidance regarding Jupyterhub setup, this is my first time installing Jupyterhub in the private server. I already followed the installation and configuration steps from the documentation, but still stuck on getting this error

jupyterhub -f /etc/jupyterhub/
[I 2021-06-16 17:53:24.083 JupyterHub app:1673] Using Authenticator: nativeauthenticator.nativeauthenticator.NativeAuthenticator
[I 2021-06-16 17:53:24.083 JupyterHub app:1673] Using Spawner: jupyterhub.spawner.LocalProcessSpawner-0.9.6
[I 2021-06-16 17:53:24.089 JupyterHub app:1016] Loading cookie_secret from /home/analyticsmdl/jupyterhub_cookie_secret
[I 2021-06-16 17:53:24.109 JupyterHub proxy:431] Generating new CONFIGPROXY_AUTH_TOKEN
[I 2021-06-16 17:53:24.131 JupyterHub app:1201] Not using whitelist. Any authenticated user will be allowed.
[I 2021-06-16 17:53:24.146 JupyterHub app:1855] Hub API listening on
[W 2021-06-16 17:53:24.147 JupyterHub proxy:472] Found proxy pid file: /home/analyticsmdl/
[W 2021-06-16 17:53:24.148 JupyterHub proxy:484] Proxy no longer running at pid=31956
[I 2021-06-16 17:53:24.149 JupyterHub proxy:567] Starting proxy @
Proxy: Fetching %s %s GET
[E 2021-06-16 17:53:24.165 JupyterHub app:1958]
    Traceback (most recent call last):
      File "/dm-var/anaconda3/envs/dev_env/lib/python3.6/site-packages/jupyterhub/", line 1956, in launch_instance_async
        await self.start()
      File "/dm-var/anaconda3/envs/dev_env/lib/python3.6/site-packages/jupyterhub/", line 1901, in start
        await self.proxy.check_routes(self.users, self._service_map)
      File "/dm-var/anaconda3/envs/dev_env/lib/python3.6/site-packages/jupyterhub/", line 57, in locked_method
        return await method(*args, **kwargs)
      File "/dm-var/anaconda3/envs/dev_env/lib/python3.6/site-packages/jupyterhub/", line 297, in check_routes
        routes = await self.get_all_routes()
      File "/dm-var/anaconda3/envs/dev_env/lib/python3.6/site-packages/jupyterhub/", line 736, in get_all_routes
        resp = await self.api_request('', client=client)
      File "/dm-var/anaconda3/envs/dev_env/lib/python3.6/site-packages/jupyterhub/", line 697, in api_request
        result = await client.fetch(req)
'   tornado.curl_httpclient.CurlError: HTTP 599: Unsupported proxy syntax in '

is there any step that I’ve missed?