Microsoft Graph ASPNET Webhooks code sample works on ngrok but not on azure
<p>I am trying the code sample from: <a href="https://github.com/OfficeDev/Microsoft-Graph-ASPNET-Webhooks" rel="nofollow noreferrer">https://github.com/OfficeDev/Microsoft-Graph-ASPNET-Webhooks</a> and it is working fine on ngrok but I get this issue on azure when creating subscription.
<a href="https://i.stack.imgur.com/Wzo4l.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Wzo4l.png" alt="enter image description here"></a></p>

<p>Any suggestions to look into?</p>