Washington/New : Microsoft said all its products were operational on Saturday after a global outage lasting more than 21 hours disrupted Outlook email and other workplace services, affecting users, businesses and government agencies across multiple countries. The company apologised to customers and business partners and attributed the disruption to a technical issue linked to an earlier network capacity upgrade.
Microsoft's service health page displayed the message ‘All products are operational’ on Saturday morning, including for Microsoft 365 business and enterprise services and consumer products.
In a post on X, the company said: “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.”
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. We are seeing broad recovery and stability across our services.This was a technical issue not related to cyber or AI / agents. The incident was introduced by an issue during an earlier network capacity upgrade that surfaced following a recent network change. We have addressed the underlying issue and continue to restore service to remaining customers and regions.Given the scale of demand, we restored services gradually, validating stability at each stage. While this took longer, it helped ensure a stable restoration.We will provide a full post-incident report once our review is complete.
The company said the disruption was caused by a technical issue linked to an earlier network capacity upgrade and ruled out a cyberattack or a problem involving artificial intelligence (AI) systems.
In a statement posted on X on Friday, Microsoft said it had addressed the underlying issue and was seeing broad recovery across its services. It added that the problem emerged when an issue from the earlier network capacity upgrade surfaced following a more recent network change.
Microsoft said it restored services in stages, checking their stability at each step. The gradual approach took longer but helped ensure a stable recovery, the company said.
Charles Lamanna, Microsoft's Executive Vice President of Copilot, Agents and Platform, said the investigation had identified technical challenges that made the recovery more difficult than usual.
“Our investigation points to technical challenges and failure modes (cascading failures + thundering herds at our network perimeter) that made recovery more difficult than normal. 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,” he said in a post on X.
I want to share what we know so far. This was not a cyberattack or an issue caused by AI tooling. Our amazing team was able to work through a very challenging situation to restore service. Our investigation points to technical challenges and failure modes (cascading failures + thundering herds at our network perimeter) that made recovery more difficult than normal. 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. We take our responsibility to our customers seriously and will do everything we can to learn from this and prevent it going forward.
Microsoft's status account said on Saturday that it was continuing to monitor the sustained recovery and would keep the systems under observation for an extended period given 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 affected several Microsoft products, including Outlook, Microsoft Teams, Copilot and other Microsoft 365 applications.
Microsoft's email platform, Exchange Online, was among the services most affected. Users reported difficulties accessing mailboxes, sending and receiving emails, managing calendars and joining or organising meetings.
The disruption also affected Microsoft 365 connectors used by OpenAI and Anthropic. Both companies reported problems with their integrations, although Microsoft clarified that AI systems were not responsible for causing the outage.
Outage-tracking platform Downdetector recorded reports from users in 74 countries and territories. In the United States, complaints about Outlook peaked at 138,058 around 1 pm Eastern Time on Thursday before declining to approximately 34,490 by the evening.
These figures represent user-submitted outage reports, not the total number of people affected.
The outage affected organisations that depend on Microsoft's cloud-based communication and productivity services.
In India, airlines including IndiGo, Air India and Akasa Air reported disruptions to email-based customer support and issued advisories to passengers. Air India temporarily rerouted its email services to ensure customer communications continued reaching the airline. Flight operations were not reported to have been affected.
Government agencies, financial institutions and businesses in several countries also faced difficulties. In the United Kingdom, the National Health Service (NHS) and police services reported problems linked to email access, while some organisations switched to alternative communication methods.
Financial and business operations were also affected. Reuters reported that some companies relied on fax machines and backup arrangements to manage communications and transactions during the disruption. Financial services firms also faced difficulties accessing research reports and conducting client interactions.
Although its service health page listed all products as operational on Saturday, Microsoft said it would continue monitoring the systems and processing delayed emails accumulated during the outage.
The outage highlighted the dependence of businesses and public institutions on a small number of cloud technology providers. It also raised questions about the resilience of systems that rely on shared infrastructure for essential services.
Microsoft said it would publish a detailed account of the incident once its technical review is complete.
(With inputs from agencies)