Unable to validate URL for Webhook

We’re setting up a new Webhook using ASP.NET Web API as the backend framework using c# and, when trying to validate the URL on zoom’s Webhook app, every time we get the error “URL validation failed. Try again later”

From what I understand, this validation is Zoom checking if the webhook endpoint actually belongs to me, so it only requires as a response the encrypted plain token and itself in Json and a return HTTP code of 200, while also responding in less than 3 seconds, I’ve re-validated all of these conditions at least 5 times. Here’s the code that generates the response:

hash = new HMACSHA256(WebhookSecret);
hashAsBytes = hash.ComputeHash(Encoding.ASCII.GetBytes(plainToken));
HashForVerify = ToHexString(hashAsBytes);
Newtonsoft.Json.Linq.JObject responseJson = Newtonsoft.Json.Linq.JObject.Parse(“{"plainToken":"” + jsonRequest.payload.First.Last.ToString() + “","encryptedToken":"” + HashForVerify + “"}”);
return Ok(responseJson); // returns IHttpActionResult (200)

When I manually try sending the request via Postman with values that we’re generated by zoom, it returns the following:

“plainToken”: “tuBN8Q39T-ej7zbbKZe5qg”,
“encryptedToken”: “f19dda16e2f7642494e8188b46c0cbe92811810c2801243c479a6d5484714874”
Status: 200 OK
Time: 114ms

Any help would be appreciated :slight_smile: