Microsoft 365 Outage Causes Widespread Disruptions Across North America
On July 23, a major outage disrupted multiple Microsoft 365 services, primarily affecting users in North America. The incident, tracked internally as MO1437424, began at approximately 10:44 AM ET.
Affected Services
The outage impacted a broad range of Microsoft platforms, including:
- SharePoint Online
- OneDrive
- Microsoft Teams
- Power Automate
- Copilot Chat
- Microsoft Loop
- Microsoft 365 Admin Center
Some reports also indicated impact on Outlook, Microsoft Store, Azure, and Defender XDR.
User Impact and Reported Issues
Users experienced a variety of service disruptions:
- Intermittent access to OneDrive
- Errors in SharePoint
- Degraded chat functionality in Teams
- Unavailable automation flows in Power Automate
- Delays in Copilot
- Inaccessible Loop pages
- Slow or unavailable Admin Center access
Regarding Outlook, users reported difficulties sending and receiving emails, with some receiving a "451 4.3.2 temporary server issue" error.
Monitoring Data
Third-party monitoring platform Downdetector recorded 2,403 user reports at 11:11 AM ET, compared to a baseline of 29. The breakdown of reports was:
- 78% concerning SharePoint
- 11% concerning Excel
- 6% concerning the Admin Center
Outage reports on similar platforms spiked around 11:40 AM PT.
Cause and Recovery Efforts
Microsoft identified the root cause as a portion of its North American service infrastructure not processing traffic as expected, leading to issues with load balancing and service availability.
The company began rerouting traffic across affected infrastructure and implementing further load balancing, which resulted in partial recovery for some customers.
Later, Microsoft stated that it had likely identified the cause and initiated testing of additional mitigation measures while monitoring service recovery. The company reported that its consumer-focused products were operational, but issues persisted for Microsoft 365 services, including Outlook.
Outage reports on third-party monitoring platforms began to decline but remained significant for services like Outlook and Microsoft 365, indicating an ongoing recovery process.
Access to Official Updates
Throughout the incident, Microsoft's official service health status page was intermittently inaccessible, frequently displaying a "429 Too Many Requests" error due to high traffic. No timeline for full recovery was announced.
Recommendations for Organizations
Microsoft advised affected organizations to review their business continuity and disaster recovery plans in light of the disruption.