Deploying Event Subscription failed

Question

Reeceiving error message when creating webhook with URL https://testchatbot002.azurewebsites.net/api/acs-webhook

Able to POST using postman with BODY

{
           "eventType": "AdvancedMessageReceived",
           "data": {
               "id": "12345",
               "content": "Hello, AI!",
               "sender": "user123"
           }
         }

When adding as webhook subscription , it failed with error message

Deployment has failed with the following error: {"code":"URL validation","message":"Webhook validation handshake failed for https://testchatbot002.azurewebsites.net/api/acs-webhook. Http POST request failed with response code Unknown. For troubleshooting, visit https://aka.ms/esvalidation. Activity id:c2509b0e-1ec9-4041-818b-57133855621b, timestamp: 3/12/2025 7:51:29 AM (UTC)."}.

Autentication type :

app = func.FunctionApp(http_auth_level=func.AuthLevel.ANONYMOUS)