Critical incident

Northwestern Information Technology: Office 365 Email and Calendaring Service Interruption

Affected: Office 365 (Email and Calendaring)

Current status of Northwestern Information Technology: Under maintenance — live Northwestern Information Technology status

Timeline

1. Aug 31, 2026, 16:10 UTC
   identified
   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. Aug 31, 2026, 17:09 UTC
   identified
   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. Aug 31, 2026, 18:11 UTC
   identified
   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. Aug 31, 2026, 19:09 UTC
   identified
   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. Aug 31, 2026, 20:06 UTC
   identified
   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. Aug 31, 2026, 22:12 UTC
   identified
   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. Aug 31, 2026, 23:26 UTC
   identified
   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. Sep 1, 2026, 13:16 UTC
   monitoring
   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. Sep 1, 2026, 15:43 UTC
   monitoring
   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. Sep 1, 2026, 17:56 UTC
    monitoring
    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. Sep 1, 2026, 20:59 UTC
    monitoring
    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. Sep 2, 2026, 16:35 UTC
    monitoring
    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. Sep 2, 2026, 21:00 UTC
    monitoring
    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. Sep 3, 2026, 16:47 UTC
    monitoring
    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. Sep 3, 2026, 19:49 UTC
    resolved
    Service has been restored to Microsoft Outlook. Microsoft has confirmed that the global issue affecting Office 365 email and calendaring service has been resolved

Updates as published by Northwestern Information Technology (original).