GET to callback URL does not return 200

[Hari Rahul]

I am using node and ngrok as mentioned in the documentation of Strava. Also using the same code as in documentation. I was able to create a subscription. But after deleting it I am not able to create subscription once again. 

callbackurl?hub.verify_token=STRAVA&hub.challenge=15f7d1a91c1f40f8a748fd134752feb3&hub.mode=subscribe

running this returns "hub.challenge": "15f7d1a91c1f40f8a748fd134752feb3"

So the GET part seems to be working but the POST is not working?

This is the full response:

{

    "message": "Bad Request",

    "errors": [

        {

            "resource": "PushSubscription",

            "field": "callback url",

            "code": "GET to callback URL does not return 200"

        }

    ]

}