Microsoft 365 Alert – Service Degradation – Exchange Online – Some users may be unable to access shared calendars in the Outlook desktop app – RESOLVED

16/07/2024 08:35:00 AM

NHSmail Reference: INC44375383

Microsoft Reference: EX814289

Issue Status: RESOLVED

Issue Description: Some users may be unable to access shared calendars in the Outlook desktop app.

More info: Users that have access to Outlook on the web or Outlook for Windows (https://www.microsoft.com/store/productId/9NRX63209R7B?ocid=pdpshare) can use this connection method to access their shared calendars without issue while we focus on remediating the problem.
Alternatively, users can bypass the impact using the method outlined in this support article: https://support.microsoft.com/en-us/office/unable-to-open-a-shared-calendar-in-outlook-desktop-c9f7b655-e4f8-4090-b103-508d451e32a4

Users that apply the workaround to their desktop client will need to re-apply it if they close or restart their client.

Final Update: 17/07/2024 08:40:00 AM – After an extended period of monitoring, coupled with internal validations and customer confirmations, they have declared the incident resolved. Microsoft understand the impact this incident has had on their users and greatly appreciate your organization”s patience, understanding, and feedback while they worked to resolve this high priority issue in its entirety.

Scope of impact: Users serviced by the affected infrastructure may be prevented from accessing shared calendars in the Outlook desktop app. Impact appears to be localized to Japan, but may be intermittent outside this region.

Root cause: A recent code change to a portion of our Directory infrastructure intended to improve overall performance contained a regression, which prevented users from opening Shared Calendars in the Outlook desktop app

Next steps: Microsoft are reviewing their code change procedures to find ways to better identify similar regressions prior to their deployment, which will help avoiding impacting customers in future updates.