U.S. technology giant Microsoft has attributed a massive, day-long global outage across its core workplace suite to an error introduced during a network capacity upgrade, apologizing to millions of affected users while firmly ruling out a cyberattack or artificial intelligence failure.
The disruption, which crippled Microsoft 365 services including Outlook, Exchange Online, Microsoft Teams, SharePoint, and Microsoft 365 Copilot across at least 74 countries, began unfolding on Thursday, November 12, 2026.
Trouble first emerged on Thursday morning in the Americas, when a separate Teams incident (tracked as TM1550488) delayed or failed chat messages between 9:45 a.m. and 10:53 a.m. ET before being resolved.
However, a far wider failure struck shortly afterward at 11:17 a.m, when Exchange Online mailboxes (incident EX1550543) began failing, rapidly cascading into a broader Microsoft 365 outage (incident MO1550821) by 1:26 p.m.
At the height of the crisis on Thursday evening, outage-tracking platform Downdetector logged nearly 140,000 user reports for Outlook alone.
Because several Microsoft 365 tools rely on Exchange Online for calendar, email, and authentication data, the failure quickly knocked out meeting scheduling in Teams, file access in SharePoint, security monitoring in Microsoft Defender XDR, and data retrieval for Copilot. Even external AI platforms, including OpenAI and Anthropic, reported disruptions to their Microsoft 365 connectors.
Initially, engineers based at Microsoft’s headquarters in Redmond, Washington, believed the disruption was driven by an “elevated load” on its servers. Further investigation revealed that a process responsible for establishing secure connections had become overwhelmed, causing servers to fail automated health checks and drop offline unexpectedly.
By 11:40 a.m. ET on Friday, November 13, after rolling back recent network configurations and extending email timeout windows to 48 hours to prevent data loss, Microsoft confirmed the underlying cause in an official update.
”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,” a Microsoft spokesperson said in the company’s Friday statement. “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.”
Addressing speculation that hackers or autonomous AI systems may have triggered the collapse, Microsoft Corporate Vice President Charles Lamanna explicitly stated that there was no indication the outage resulted from “malicious or cyber activity.”
Across the United States, the ripple effects quickly reached public safety and local government operations. In Colorado, the Arapahoe County Sheriff’s Office warned that inmate releases were temporarily delayed because staff could not receive Outlook email notifications required to process online bond payments, while in North Carolina, the Greensboro Police Department also reported widespread email blackouts before services were restored.
The disruption extended equally across the Atlantic and into the Asia-Pacific region, paralyzing daily operations across businesses, financial markets, airlines, and public institutions.
In the United Kingdom, Cyber Minister Baroness Elizabeth Lloyd confirmed the British government was working directly with Microsoft to assess public-sector fallout, noting that while emergency 999 and NHS 111 lines remained operational, government back-office communications were heavily disrupted. Meanwhile, offices across Australia, India, and South Korea lost email access throughout Friday’s workday.
Prins Ralston, CEO of the Australian Computer Society (ACS), called for a national review of sovereign IT risk, warning that small businesses and critical services are overly exposed when a single cloud provider falters.
In India, the country’s largest airline reported that its customer email support channels were knocked offline, and financial brokerages across the region struggled to host client calls during quarterly earnings announcements.
By Friday afternoon in the U.S., Microsoft reported “signs of sustained recovery” with email queues returning toward normal levels, though it warned that intermittent delays could persist while residual traffic cleared. The company has pledged to publish a full post-incident root-cause report once full stability is verified across all global regions.
