login fail ERROR: Expecting value: line 1 column 1 (char 0)

#st2 --debug login st2admin -p 'Ch@ngeMe'

-------- begin 140218091069512 request ----------

curl -X POST -H 'User-Agent: python-requests/2.23.0' -H 'Accept-Encoding: gzip, deflate' -H 'Accept: /' -H 'Connection: keep-alive' -H 'content-type: application/json' -H 'Content-Length: 2' -H 'Authorization: Basic c3QyYWRtaW46Q2hAbmdlTWU=' --data-binary '{}' http://127.0.0.1:9100/tokens

-------- begin 140218091069512 response ----------

<title>Node Exporter</title>

Node Exporter

Metrics

# -------- end 140218091069512 response ------------

ERROR: Expecting value: line 1 column 1 (char 0)

CLI settings:

Config file path: /root/.st2/config
Client settings:

ST2_BASE_URL: http://127.0.0.1
ST2_AUTH_URL: http://127.0.0.1:9100
ST2_API_URL: http://127.0.0.1:9101/v1
ST2_STREAM_URL: http://127.0.0.1:9102/v1
ST2_AUTH_TOKEN: None

Proxy settings:

HTTP_PROXY:
HTTPS_PROXY:

Traceback (most recent call last):
File "/opt/stackstorm/st2/lib/python3.6/site-packages/st2client/shell.py", line 408, in run
func(args)
File "/opt/stackstorm/st2/lib/python3.6/site-packages/st2client/commands/auth.py", line 154, in run_and_print
self.run(args, **kwargs)
File "/opt/stackstorm/st2/lib/python3.6/site-packages/st2client/commands/auth.py", line 125, in run
manager = self.manager.create(instance, auth=(args.username, args.password), **kwargs)
File "/opt/stackstorm/st2/lib/python3.6/site-packages/st2client/models/core.py", line 42, in decorate
return func(*args, **kwargs)
File "/opt/stackstorm/st2/lib/python3.6/site-packages/st2client/models/core.py", line 309, in create
instance = self.resource.deserialize(response.json())
File "/opt/stackstorm/st2/lib/python3.6/site-packages/requests/models.py", line 898, in json
return complexjson.loads(self.text, **kwargs)
File "/opt/stackstorm/st2/lib/python3.6/site-packages/simplejson/init.py", line 525, in loads
return _default_decoder.decode(s)
File "/opt/stackstorm/st2/lib/python3.6/site-packages/simplejson/decoder.py", line 370, in decode
obj, end = self.raw_decode(s)
File "/opt/stackstorm/st2/lib/python3.6/site-packages/simplejson/decoder.py", line 400, in raw_decode
return self.scan_once(s, idx=_w(s, idx).end())
simplejson.errors.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

Start with st2client/commands/auth.py and st2client/models/core.py, then reproduce the shown #st2 --debug login request against the /tokens endpoint. Compare the response returned by the configured authentication URL with the JSON expected by response.json(); done means the reported login failure has a defined, verified resolution.