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Microsoft Exchange Online outage affecting global users mitigated

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📰 1 unique sources, 1 articles

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Microsoft confirmed a global outage affecting Exchange Online users, preventing access to emails and calendars. The issue began early on September 11 and was resolved by September 12. The outage was caused by a specific software build version that led to repeated database dismounts and failovers, resulting in increased CPU utilization and message queue buildup. The outage affected users in North America initially, but later expanded to a global scale. Users experienced server connection problems, impacting access to Teams, Outlook, and Hotmail. Microsoft implemented configuration changes to mitigate the issue and restored most of the degraded infrastructure.

Timeline

  1. 11.09.2025 22:43 📰 1 articles · ⏱ 5d ago

    Microsoft mitigates global Exchange Online outage

    On September 11, Microsoft confirmed an outage affecting Exchange Online users worldwide. The issue, caused by high CPU utilization and message queue buildup due to a specific software build version, was resolved by September 12. Users experienced server connection problems, impacting access to emails, calendars, and other services like Teams, Outlook, and Hotmail. The outage was initially region-specific but later expanded globally.

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