Microsoft users faced widespread service disruptions on Thursday as outages hit Exchange Online mailboxes and Microsoft Teams.
The incidents, which impacted users across North America and potentially other regions, forced the company to scramble to restore connectivity.
Exchange Online Server Unavailability
The primary disruption involved users struggling to access Exchange Online mailboxes through various connection methods. According to abcnews.com, Microsoft initially suspected an "elevated load" across its infrastructure was causing the connectivity failures.
We're investigating reports of users experiencing issues accessing Exchange Online mailboxes through multiple connection methods in the Americas. More details can be found in the Microsoft 365 admin center under EX1550543.
However, the company later clarified that the issue was not caused by a surge in traffic. Instead, Microsoft reported that a number of servers became "unexpectedly unavailable," which strained the remaining infrastructure.
To address the backlog, the company paused all deployments and redirected traffic away from the affected servers. By 4 p.m. Thursday, Microsoft stated it had validated a new service health check method that allowed a subset of servers to return to service.
We're investigating reports of users experiencing issues when accessing or using Microsoft Teams functionality in North America, and more details can be found in the Microsoft 365 admin center under TM1550488.
Microsoft Teams Service Restoration
While Exchange Online issues persisted into the afternoon, the company reported a faster resolution for its collaboration platform. “Our mitigative actions have successfully restored service health and functionality,” Microsoft announced regarding Microsoft Teams in North America, abcnews.com reported.
Downdetector, a platform that tracks real-time service status, confirmed that users were experiencing issues with both Teams and Outlook throughout the day. The company acknowledged that the Exchange Online mailbox problems could potentially affect Microsoft 365 service connectivity for users in any global region.
Microsoft Engineers Use Automated Systems to Manage Instability
Microsoft engineers focused on automated recovery systems to manage the ongoing instability. The company stated it was preparing these systems to "continually detect and restart unresponsive servers" to maintain stability as the broader infrastructure changes were implemented.
The company continued to provide updates throughout the day as it pursued pathways to reduce the impact on users. As of late Thursday, Microsoft indicated that its attempts to fix the mailbox issues were showing signs of success, though the situation remained a developing story.
We've determined a portion of infrastructure is experiencing elevated load across multiple regions, which is likely contributing to the connectivity errors. We're providing more information under EX1550543 and MO1550821 in the Microsoft 365 admin center, as well as…
What Caused the Microsoft 365 Connectivity Issues?
What caused the Microsoft 365 connectivity issues?
“We determined the elevated load isn't driven by an increase in traffic, but by a number of servers being unexpectedly unavailable; straining the remaining infrastructure,” Microsoft clarified. This created an elevated load on the remaining, functional infrastructure.
Which services were affected by the outage?
Users reported issues accessing Exchange Online mailboxes and Microsoft Teams. Downdetector also noted disruptions to other Microsoft 365 products during the same period.
Are the services fully restored?
Microsoft reported that Teams functionality was restored quickly on Thursday. For Exchange Online, the company said that it was applying fixes to servers and seeing signs of success by late afternoon, though it continued to monitor the situation.
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