Invalid `checksum`

def start():
    # login url: 'https://kite.trade/connect/login?api_key=xxxxxxxxxxxxxxxx&v=3'

    # Collect request token from url which is redirected from the login url
    request_token = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"                     # Cross checked

    # Collect api_key and api_secret from the app
    api_key = "xxxxxxxxxxxxxxxx"                                          # Cross checked
    api_secret = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"                       # Cross checked

    kite = KiteConnect(api_key=api_key)
    session = kite.generate_session(request_token=request_token, api_secret=api_secret)

I'm trying to generate a session to obtain an access_token. Invalid `checksum` is the error I'm being hit with. Is there any issue I need to fix or is it the problem at the sever end?
P.S. I recently created a new app(2nd) and this issue begun to show up. I've cancelled my first app's subscription a month ago. I'm trying to run this around mid-night on a weekend