Graph API returns responseStatus: none for accepted meetings (Exchange Online / Resource Mailbox)

Question

We’re running into a really specific, intermittent issue with our Graph integration that we need help investigating. We’re seeing cases across multiple tenancies and rooms, where the data between the Room and the Organizer isn't syncing up correctly.

Most of the time, the flow works fine: an Organizer books a room, the Room auto-accepts, and the Organizer’s event updates to show the room as "Accepted."

However, intermittently, the process breaks at the last step. The Room receives the invite and puts it on its calendar (we can see it there), but the Organizer’s copy of the event never gets updated. When we query the Organizer’s event via Graph, the room’s responseStatus is still stuck at none.

We have already verified the following to rule out common errors:

Response Requested: We confirmed isResponseRequested is definitely set to True on these events.

Room Settings: The room is definitely set to AutoAccept processing.

Permissions: This is a standard invitation flow. The organizer does not have "Direct Booking" (BookInPolicy) permissions, so this should trigger a standard email response workflow.

The Event Exists: We can query the room's calendar and see the event sitting there, so the room definitely accepted it.

It looks like the "Accepted" signal from the Room isn't making it back to the Organizer's item, or the backend sync is failing silently. Since this happens intermittently across different users and rooms, we suspect a race condition in the Resource Booking Assistant or a delay in the backend info-worker sync.

Answer 1

Does the organizer actually receive the meeting acceptance email? There is no other update mechanism apart from said message being sent, so in effect this is how the client (and the user) know the meeting has been accepted. You can run a message trace to confirm the delivery: https://learn.microsoft.com/en-us/exchange/monitoring/trace-an-email-message/message-trace-modern-eac

Answer 2

The issue you're experiencing with the Graph API returning responseStatus: none for accepted meetings in Exchange Online could be related to several factors, particularly concerning the configuration of the resource mailbox and the synchronization process between the organizer's calendar and the room's calendar.

Here are some points to consider:

1. Resource Mailbox Configuration: Ensure that the resource mailbox is correctly configured to respond automatically to meeting invitations. You can check this by using the following PowerShell cmdlet:

      Get-CalendarProcessing <Identity> | fl AutomateProcessing
   

   The AutomateProcessing attribute should be set to AutoAccept.
2. Corrupted Free/Busy Data: Sometimes, issues with free/busy data can cause synchronization problems. It may be beneficial to update the free/busy information for the resource mailbox. This can be done using MFCMapi to delete certain files in the Free/Busy folder.
3. Race Conditions: As you suspected, intermittent issues like this can sometimes be attributed to race conditions in the Resource Booking Assistant or delays in backend synchronization processes. This can happen if the response from the room is not processed in time before the organizer's calendar is updated.
4. Permissions and Policies: Since you've confirmed that the organizer does not have direct booking permissions, ensure that the policies governing the resource mailbox allow for proper communication and response handling between the room and the organizer's calendar.
5. Monitoring and Logging: If possible, enable logging for the resource mailbox to capture any errors or unusual behavior during the booking process. This might provide insights into why the response is not being sent back to the organizer's event.

If the problem persists, consider reaching out to Microsoft support for further assistance, as they may have more detailed insights into backend processes that could be affecting your integration.

---

References:

• A resource doesn't respond to meeting requests when using Resource Booking to schedule the resource