"Subscription validation request failed. Notification endpoint must respond with 200 OK to validation request"

Question

I finished this tutorial https://docs.microsoft.com/en-us/graph/tutorials/azure-functions?tutorial-step=5 everything worked fine until i published my azure Functions in my Azure App. When i try to make the subscription i get this error "Subscription validation request failed. Notification endpoint must respond with 200 OK to validation request". When i test with ngrok i can create the subscription with no problems but when i replace NgrokURL value for my Azure function Url, not. Is that the right way to create the susbcription? Also i tried to create the subscription in Graph Explorer but i still get this message.

Answer 1

In the following below code, content type must be text/plain.
body must include the validation token. 1. CodeSamples asp .net mvc sample - Specifically look at the NotificationController.cs file In the method

[HttpPost]  
public async Task<ActionResult> Listen()  
{
// Validate the new subscription by sending the token back to Microsoft Graph.
// This response is required for each subscription.
if  (Request.QueryString["validationToken"]  !=  null)
{
var token =  Request.QueryString["validationToken"];
return  Content(token,  "plain/text");
}

2. notificationUrl must be capable of responding to the validation request. Also, you need to make sure that the validation token returns as plain/text. Please refer to the Notification endpoint validation document for details.

3. Try isolating the code and use Postman/Graph Explorer to call same API and observe results.