💡 Our Technical Review in summary
1. Summary
Microsoft resolved an issue where users were unable to access the Exchange admin center (EAC). The disruption was caused by a specific section of infrastructure performing below acceptable performance thresholds. Engineers successfully mitigated the issue by redirecting affected traffic to healthy alternate infrastructure.
2. Impact
Impact was limited to a subset of users attempting to access the EAC between 9:06 AM UTC and 11:12 AM UTC on January 28, 2026. During this window, affected administrators may have experienced failures or significant delays when trying to load the management portal.
3. Status
Service Restored. Microsoft has confirmed the resolution following a period of monitoring. Performance levels have returned to normal, and no further actions are required from IT administrators. A post-incident review of performance data is underway to prevent recurrence.
Microsoft Official Issue Details
User Impact
Users may have been unable to access the EAC.
Status: serviceRestored
Service: Exchange Online
Classification: advisory
Origin: microsoft
Updates
- 2026-01-28 12:39
Title: Some users may have been unable to access the Exchange admin center (EAC)User impact: Users may have been unable to access the EAC.
Final status: We’ve identified that a section of infrastructure, responsible for facilitating EAC access, unexpectedly began performing below acceptable performance thresholds and caused impact. We’ve redirected affected traffic to alternate healthy infrastructure and confirmed impact is no longer occurring after a period of monitoring.
Scope of impact: Impact was specific to some users who were served through the affected infrastructure attempting to access the EAC.
Start time: Wednesday, January 28, 2026, at 9:06 AM UTC
End time: Wednesday, January 28, 2026, at 11:12 AM UTC
Root cause: A section of infrastructure, responsible for facilitating EAC access, unexpectedly began performing below acceptable performance thresholds and caused impact.
Next steps:
– We’re reviewing performance data and trends on the affected systems to help prevent similar impact from happening again.This is the final update for the event.
- 2026-01-28 11:29
Title: Some users may be unable to access the Exchange admin center (EAC)User impact: Users may be unable to access the EAC.
Current status: We’re continuing to review service monitoring telemetry to isolate the root cause and develop a remediation plan.
Scope of impact: Impact is specific to some users who are served through the affected infrastructure attempting to access the EAC.
Next update by: Wednesday, January 28, 2026, at 2:00 PM UTC
- 2026-01-28 09:49
Title: Some users may be unable to access the Exchange admin center (EAC)User impact: Users may be unable to access the EAC.
Current status: We’re reviewing service monitoring telemetry to isolate the root cause and develop a remediation plan.
Scope of impact: Impact is specific to some users who are served through the affected infrastructure attempting to access the EAC.
Next update by: Wednesday, January 28, 2026, at 12:00 PM UTC
