Unable to cancel intraday order, returns 500 status code

Bugs
1

I have been trying to cancel order, and i am repeatedly getting many 500 errors without any error message for more than a week now.

URL https://developer.paytmmoney.com/orders/v1/cancel/regular
Here is the request body

{
  "txn_type": "S",
  "source": "N",
  "exchange": "NSE",
  "segment": "E",
  "product": "I",
  "security_id": "335",
  "quantity": 65,
  "validity": "DAY",
  "order_type": "LMT",
  "price": 3042.5,
  "off_mkt_flag": false,
  "mkt_type": "NL",
  "order_no": "168**********",
  "serial_no": 1,
  "group_id": "1"
}

Here is the response

{"status":500,"message":"Unexpected Error","error_code":"PM_OPEN_API_500"}

What is the issue?
How to find correct group id? Should this be string or number? Is there any detail document about group id?