ERROR - Error returning OAuth user info

We are trying to use Okta Oauth for Airflow authentication, but we are unbale to login to the airlow applicaion

Environment

Flask-Appbuilder version: 3.2.2 Authlib : 0.15.5 Airflow Version: apache/airflow:2.1.0-python3.8

Describe the expected results

Okta OAuth should be able to authenticate and redirect to the Airflow home page

Describe the actual results:

Error log: “views.py: ERROR - Error returning OAuth user info: Expecting value: line 1 column 1 (char 0)” On Airlow login page : Invalid login. Please try again.

Steps to reproduce

We have the below code for authentication in webserver_config.py

import os
import logging
logger = logging.getLogger(__name__)
logger.setLevel(logging.DEBUG)

from airflow import configuration as conf
from flask_appbuilder.security.manager import AUTH_OAUTH

basedir = os.path.abspath(os.path.dirname(__file__))

# Flask-WTF flag for CSRF
WTF_CSRF_ENABLED = True
AUTH_ROLE_ADMIN = 'Admin'
AUTH_USER_REGISTRATION = True
AUTH_USER_REGISTRATION_ROLE = "Admin" 
AUTH_TYPE = AUTH_OAUTH

OAUTH_PROVIDERS = [
{'name': 'okta', 'icon': 'fa-circle-o',
    'token_key': 'access_token',
    'remote_app': {
        'client_id': '--X--X--',
        'client_secret': '--X--X--',
        'server_metadata_url': 'https://<okta-url>/.well-known/openid-configuration',
        'api_base_url': 'https://<okta-url>/oauth2/v1',
        'client_kwargs': {
            'scope': 'openid profile email groups'
        },
        'access_token_url': 'https://<okta-url>/oauth2/v1/token',
        "userinfo_url": "https://<okta-url>/oauth2/default/userinfo",
        'authorize_url': 'https://<okta-url>/oauth2/v1/authorize',
        "redirect_uris": [
            "http://<URL>/",
            "http://<URL>/oidc/callback"
            ]
    }
}]

AUTH_ROLES_SYNC_AT_LOGIN = True
PERMANENT_SESSION_LIFETIME = 1800