Sandbox Callback

Did you find a solution ??

Callbacks are affected by below:

1. Callback URL Certificate used must be from a trusted intermediate CA (Most important).

2. Callback URL should be using https
3. Callback URL should be on port 443
4. If your URL is unresponsive or returns status code other than 200, it can get blocked

5. Not sending the X-Callback-Url header in the request.

Recommendation:
Since (1) above is a bit tricky for sandbox, you can try using a callback URL from sites like (https://hookdeck.com/). From such a site you can redirect the callback to your actual URL .