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[sandbox] Webhook creation failing - how do I resolve "Webhook is not reachable" error?
Tags: webhooks
Jan 27, 2017 at 6:09pm   •   5 replies  •  0 likes

I'm using the Ruby SDK to make a POST request to create a subscription in the sandbox environment. The WebHook address is a local tunnel to my local app server, and I see the request coming through and responding with 200 OK.

Here's the error I'm getting from the request to the subscription API:

SUB-521 WebHook is not reachable

It is reachable, and the request is completing, after successfully sending the Verification-Token header. (Otherwise I would be getting SUB-520 I believe.)

Any clues what's going wrong? Is there some sort of payload it is expecting to receive beyond the Verification-Token?

Additional info:

request uri =>

app key => nDaskd-URlGBOsj0N4Ilnw

5 Answers
answered on Jul 17, 2017 at 9:59am  
Hi, we are using server which is live and still getting  'SUB-521', message: 'WebHook is not reachable'. but thing is that if we try after 5 seconds it works perfectly fine.

answered on Mar 14, 2017 at 9:04pm  
Thank you all for your prompt response. Today i am able to create subscription successfully in the same setup. What i just did is uninstall the ngrok and reinstalled and tried out :-)

answered on Mar 14, 2017 at 10:05am  
I have this application (written in Node.js) which shows how to setup Webhooks and receive the event notifications from them properly.

Additionally, this has a one-button Heroku deployment (which makes it really easy to get started using/testing with this quickly).

answered on Mar 13, 2017 at 7:03am  
I am too facing similar problem. 

  1. The request is coming through successfully, via the internet.
  2. Using ngrok for local tunnel
  3. From the server perspective, the response is around ~300 ms each time.
  4. I am indeed capturing and returning the 'Validation-Token'.(200 status)

Getting below response


  "errorCode" : "SUB-521",

  "message" : "WebHook is not reachable",

  "errors" : [ {

    "errorCode" : "SUB-521",

    "message" : "WebHook is not reachable"

  } ]


Till last week it was working in the same setup. Today only it is not working. 

Is there any issue in creating a subscription.

Could anyone help me


answered on Jan 28, 2017 at 6:18am  
Have you read the doc here: ?

The webhook URL service must meet the following requirements:
  1. is available on the Internet
  2. has a TLS / SSL enabled*
  3. can respond within 1000 milliseconds
  4. will respond with Validation-Token header on subscription
Please make sure that webhook url meets all the requirements above. 


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