Office 365 Email and Calendaring Service Interruption

Update timeline

1. identified Aug 31, 2026, 04:10 PM UTC

   Northwestern Information Technology has identified an issue and Office 365 Email is unavailable. While the vendor is working to resolve this issue as quickly as possible, we have not yet received a projected resolution time. The next update will be provided by 12:15 CDT.

2. identified Aug 31, 2026, 05:09 PM UTC

   The vendor continues working to resolve this issue as quickly as possible; however, we have not yet received a projected resolution time. The next update will be provided by 13:15 CDT.

3. identified Aug 31, 2026, 06:11 PM UTC

   The vendor has identified a potential corrective action for the affected infrastructure and is evaluating deployment options at this time. The next update will be provided by 14:15 CDT

4. identified Aug 31, 2026, 07:09 PM UTC

   Microsoft has identified a potential remediation and is performing tests to ensure its efficacy before applying it more broadly. They also report additional services may be affected, including OneDrive, SharePoint, and Teams Calendaring. The next update will be provided by 15:15 CDT.

5. identified Aug 31, 2026, 08:06 PM UTC

   Microsoft continues working to resolve this issue as quickly as possible; however, we have not yet received a projected resolution time. The next update will be provided by 17:30 CDT.

6. identified Aug 31, 2026, 10:12 PM UTC

   Microsoft continues review of affected infrastructure and recent changes made to the service to definitively confirm the cause of impact. They continue to test and implement various mitigation strategies to apply the necessary authentication component, which have so far yielded positive results. They're monitoring these tests and mitigative actions closely and will provide an estimated time to resolution as soon as one is available. The next update will be provided by 18:30 CDT.

7. identified Aug 31, 2026, 11:26 PM UTC

   Microsoft continues working to resolve this issue as quickly as possible; however, we have not yet received a projected resolution time. The next update will be provided by September 1, 2026 - 8:30 CDT,

8. monitoring Sep 01, 2026, 01:16 PM UTC

   Microsoft is reporting service restoration is underway across affected infrastructure but have not yet provided an all-clear status for this incident. Northwestern Information Technology has monitored service restoration to our affected services as well and will continue to monitor while awaiting confirmation from Microsoft this incident is resolved. Next update will be by 12:00 CDT

9. monitoring Sep 01, 2026, 03:43 PM UTC

   Microsoft reports that service restoration is underway across the affected infrastructure but has not yet provided an all-clear status for this incident. We continue to see service restoration for affected services across the University, though some users may still experience intermittent issues as Microsoft works toward full resolution. We will continue to monitor services while awaiting Microsoft's confirmation that this incident is resolved. The next update will be provided by 13:00 CDT.

10. monitoring Sep 01, 2026, 05:56 PM UTC

    Microsoft reports that service restoration is underway across the affected infrastructure but has not yet provided an all-clear status for this incident. We continue to see service restoration for affected services across the University, though some users may still experience intermittent issues as Microsoft works toward full resolution. We will continue to monitor services while awaiting Microsoft's confirmation that this incident is resolved. The next update will be provided by 16:00 CDT.

11. monitoring Sep 01, 2026, 08:59 PM UTC

    Microsoft reports that service restoration continues across the affected infrastructure but has not yet provided an all-clear status for this incident. We continue to see service restoration for affected services across the University, though some users may still experience intermittent issues as Microsoft works toward full resolution. We will continue to monitor services while awaiting Microsoft's confirmation that this incident is resolved. The next update will be provided by 12:00 CDT on Wednesday, September 2.

12. monitoring Sep 02, 2026, 04:35 PM UTC

    Microsoft reports that service restoration continues across the affected infrastructure but has not yet provided an all-clear status for this incident. We continue to see service restoration for affected services across the University, though some users may still experience intermittent issues as Microsoft works toward full resolution. We will continue to monitor services while awaiting Microsoft's confirmation that this incident is resolved. The next update will be provided by 16:00 CDT.

13. monitoring Sep 02, 2026, 09:00 PM UTC

    Microsoft reports that service availability remains above 99 percent, and its monitoring shows the impact has been resolved for the majority of users. However, service restoration continues across the remaining affected infrastructure. We continue to see service restoration for affected services across the University, though some users may still experience intermittent issues as Microsoft works toward full resolution. We will continue to monitor services while awaiting Microsoft's confirmation that this incident is resolved. The next update will be provided by 12:00 CDT, on Thursday, September 3.

14. monitoring Sep 03, 2026, 04:47 PM UTC

    Microsoft reports that, while monitoring service telemetry, it identified a small number of errors affecting mail flow. Microsoft is conducting targeted service restarts to reduce these errors and mitigate their impact. In parallel, Microsoft is continuing to analyze service health telemetry to determine whether any additional mitigation actions are required to fully restore normal functionality. Northwestern Information Technology continues to see service restoration for affected services across the University, though some users may still experience intermittent issues as Microsoft works toward full resolution. We will continue to monitor the situation and provide updates as new information becomes available. The next update will be provided by 16:00 CDT.

15. resolved Sep 03, 2026, 07:49 PM UTC

    Service has been restored to Microsoft Outlook. Microsoft has confirmed that the global issue affecting Office 365 email and calendaring service has been resolved