Outlook Push Notifications REST API fails in subscriptions registration - outlook

Question

My application uses Outlook Push Notifications REST API to get updates for a set of users.
The code I use to make the registration is like following:
HTTP POST to:
https://outlook.office.com/api/v2.0/users/<user email>/subscriptions
POST data = {
'#odata.type': '#Microsoft.OutlookServices.PushSubscription',
'Resource': 'https://outlook.office.com/api/v2.0/me/messages',
'NotificationURL': 'https://<my_valid_hostname>/api/subscriptions',
'ChangeType': 'Created, Deleted',
'ClientState': <user UUID>,
}
This code always worked fine, but since Sep 26 it stopped to work for mostly of users. The HTTP request to make a registration to web notification returns HTTP 403 error:
HTTP 403 Error: https://outlook.office.com/api/v2.0/users/<user email>/subscriptions
{
"error": {
"code": "ErrorAccessDenied",
"message":"Access is denied. Check credentials and try again."
}
}
This application is a backend aplication registered in Azure AAD portal and uses a token which allow me to do the requests on behalf of the users.
My token credentials are working fine. I use the same token for Graph API and Outlook API without errors. I refreshed it to see if the error go away, but it doesn't work. The error comes for fresh tokens anyway.
For some users I get no error, it always work. The subscription is created fine and I get the subscription data in JSON returned, as usual.
This make me think that it may be a problem in Microsoft side, but I have no way to check this.
So how can I fix this error for the affected users?

Answer 1

First thing that comes in my mind is that did you forgot to renew your calendar subscriptions? It's something like max. 14 days those are alive. Anytime before expiration you can renew subscriptions and after that you still can revive subscriptions.
In fact now I tested new subscription with my app and I get only 7 days to expiration date.
At this point I got that you are getting error when creating new subscription.. are you sure your access_token is still valid?

Answer 2

For future SO users,
POST https://outlook.office.com/api/v2.0/me/subscriptions
Content-Type: application/json
Authorization: Bearer <access_token>
{
"#odata.type":"#Microsoft.OutlookServices.PushSubscription",
"Resource": "https://outlook.office.com/api/v2.0/<Outlook-Resource>",
"NotificationURL": "<My-Endpoint-Url>",
"ChangeType": "Created,Updated,Deleted"
}
Optional ClientState in body, allows the listener to check the legitimacy of the notification.
Check out the docs for more info.