500 internal server about proxmoxer HOT 5 OPEN

$ pveversion
pve-manager/5.2-12/ba196e4b (running kernel: 4.15.18-9-pve)

---------------------------------------------------------------------------
ResourceException                         Traceback (most recent call last)
<ipython-input-35-7a21cf167f34> in <module>
      1 for node in proxmox.nodes.get():
----> 2     for vm in proxmox.nodes(node['node']).qemu.get():
      3         print(vm)
      4
      5

~/.virtualenvs/proxmox-dokuwiki-exporter/lib/python3.7/site-packages/proxmoxer/core.py in get(self, *args, **params)                                                                                                              
     82
     83     def get(self, *args, **params):
---> 84         return self(args)._request("GET", params=params)
     85
     86     def post(self, *args, **data):

~/.virtualenvs/proxmox-dokuwiki-exporter/lib/python3.7/site-packages/proxmoxer/core.py in _request(self, method, data, params)                                                                                                    
     77         if resp.status_code >= 400:
     78             raise ResourceException("{0} {1}: {2}".format(resp.status_code, httplib.responses[resp.status_code],                                                                                                          
---> 79                                                           resp.content))
     80         elif 200 <= resp.status_code <= 299:
     81             return self._store["serializer"].loads(resp)

ResourceException: 500 Internal Server Error: