Microsoft 365 outage disrupts Outlook, Teams and other apps for nine hours

Microsoft 365 services, including Outlook and Teams, were unavailable for more than nine hours on Thursday and Friday, affecting thousands of users worldwide.

The disruption was reported around 1 pm ET, with Down Detector recording nearly 130,000 problem reports across 74 countries. Affected services included Word, Excel, PowerPoint, SharePoint, OneDrive and the AI assistant Copilot.

Microsoft said it had “no indication of a cyber‑attack” and suggested the outage stemmed from mis‑configured settings on servers that keep Microsoft 365 running. The company attempted several remedies, such as rolling back updates and limiting traffic to the affected servers.

Mark Gregory, an associate professor at RMIT University, explained the issue appeared to be a network‑layer configuration problem similar to the 2023 Optus outage. He warned that when part of a server pool fails, remaining servers become overloaded, leading to a cascading failure.

Gregory urged businesses to invest in testing environments for configuration changes and to maintain backup options, noting the global impact on productivity when cloud services go down.

Microsoft later announced that Teams had been “successfully restored” in North America, though some users continued to experience connectivity problems.

Source: Irish Examiner. Photo: panumas nikhomkhai / Pexels.