Microsoft’s services were fully restored on Saturday after a massive global outage disrupted Outlook email and other workplace tools, with the company apologising to customers and attributing the incident to a network capacity upgrade issue.
The company’s service health page displayed the message “All products are operational” on Saturday morning, covering Microsoft 365 business and enterprise services as well as consumer products.
“We are deeply sorry for the disruption this incident has caused our customers and partners. We know the trust they place in our services and take that responsibility extremely seriously,” Microsoft said in a post on X.
The company said the outage was caused by a technical issue and was not related to cyber activity, artificial intelligence or AI agents. The problem originated during an earlier network capacity upgrade and surfaced after a recent network change, it said.
Microsoft said it had addressed the underlying issue but restored services gradually, checking stability at each stage because of the scale of demand. The phased restoration took longer but helped ensure services remained stable, it said.
Charles Lamanna, Microsoft’s Executive Vice President of Copilot, Agents and Platform, said the investigation had identified technical challenges, including cascading failures and “thundering herds” at the network perimeter, which complicated the recovery process.
“I’m working closely with the engineering team to complete the full post-mortem. We will publish the post-mortem shortly covering the step-by-step timeline and our many repair items to avoid similar outages in the future,” Lamanna said in a post on X.
Microsoft’s service status account said on Saturday that it was continuing to monitor the restored services over an extended period because of the severity of the incident. It was also tracking the backlog of emails accumulated during the outage to ensure they were processed before declaring the issue fully resolved.
The outage, which began late on Thursday, affected businesses across the world, including Indian airlines and financial services firms.
Domestic carriers IndiGo, Air India and Akasa Air reported disruptions to their email-based customer support, affecting their ability to receive or respond to some passenger queries. Air India temporarily rerouted its email services to ensure customer communications continued to reach the airline. Flight operations were not reported to have been affected.
Financial services firms also faced difficulties accessing research reports and conducting client interactions.
The disruption primarily affected Microsoft 365 features linked to Exchange Online, the company’s cloud-based email platform. Users faced difficulties accessing mailboxes through Outlook on the web and desktop applications, while email delivery was delayed.
At its peak, the outage generated more than 1.3 lakh reports of Outlook-related problems on outage-tracking platform Downdetector. Disruptions were reported across 72 to 74 countries.
(With inputs from PTI)
