Microsoft 365 Alert : Service Degradation – Exchange Online – Users are unable to check availability of meetings when using a custom Microsoft Graph API in Exchange Online – RESOLVED

Announcements Sourav Nandi

14/10/2022 08:41:00 AM (BST)

NHSmail Reference : INC32138465

Microsoft Reference : EX445386

Issue Status : RESOLVED

Issue Description : Users were unable to check availability of meetings when using a custom Microsoft Graph API in Exchange Online.

More info : Impact was specific to the findMeetingTimes Graph API app endpoint on both Production v1.0 and Beta. Impacted users received an AttendeesUnavailableOrUnknown response, and this issue happened when passing two or more attendees.

To bypass the problem, the app owners or developers could have utilized either of the following options:

a) Instead of findMeetingTimes, use getSchedule for getting the free/busy availability information z

b) findMeetingtimes will work when passing one attendee.

Scope of impact : Users attempting to check availability of meetings when using a custom Microsoft Graph API app in Exchange Online were affected.

Final Update : 19/10/2022 13:35:00 PM – Microsoft confirmed that their fix addressing the coding incompatibility issue has fully saturated throughout the affected environment, restoring all users’ ability to check meeting availability when using a custom Microsoft Graph API in Exchange Online.

Root cause : A coding incompatibility issue during a recent deployment test to improve the findMeetingTimes API is resulting in availability for meetings to not show up when using a custom Microsoft Graph API.

Next steps : Microsoft is reviewing their update testing methodology to prevent the introduction of similar coding incompatibility issues in future deployments.