Microsoft global service outage disrupts Outlook, Teams and cloud applications

A global Microsoft service outage occurred on Thursday, November 12, 2026, affecting a wide range of email and cloud applications. The disruption impacted critical services including Outlook, Exchange Online, Microsoft 365, Teams, Copilot, and Defender. Users in the Americas, the United States, and various other global regions experienced significant service interruptions.

Widespread service disruptions

The outage caused significant operational challenges across multiple sectors. Schools in Australia and businesses in the United States reported disruptions due to the inability to access essential digital tools. The impact extended beyond standard productivity software, affecting Microsoft Defender security software and Intune dashboards. Additionally, the outage affected cloud-based Windows computers and third-party interfaces, including those used by OpenAI and Anthropic.

Downdetector reported approximately 130,000 reports regarding Outlook shortly after 1:00 PM ET on November 12, 2026. Microsoft identified the specific incident under the identification code EX1550543. While the disruption occurred while the Cybersecurity and Infrastructure Security Agency (CISA) was monitoring a zero-day vulnerability, CVE-2026-124194, Microsoft stated there is no evidence of malicious activity, cyberattacks, or issues related to AI/agents regarding this specific incident.

Technical causes and recovery

Microsoft reported that servers were unavailable and failing automatic health checks. The company attributed these failures to elevated traffic on parts of its infrastructure. Microsoft engineers attempted to recover services by attempting to redistribute traffic and restarting the affected infrastructure. The company stated, "We are working to safely return services to operation and is investigating traffic management imbalances."

The duration of the downtime was significant for many users. Doug Madory, the Director of internet analysis at Kentik, reported that traffic began returning after approximately 18 hours of downtime. The technical failure resulted in a period of instability before services stabilized across the global network.

Impact on third-party interfaces

The scope of the Microsoft outage reached into the broader artificial intelligence ecosystem. Because several prominent AI platforms rely on Microsoft infrastructure, the disruption affected the interfaces for OpenAI and Anthropic. This connectivity issue meant that users of these third-party services faced limitations during the outage period. The incident highlighted the interconnected nature of modern cloud-based software and artificial intelligence services.

Glossary

• Exchange Online — Exchange Online is Exchange Server delivered as a cloud service hosted by Microsoft itself. It is built on the same technologies as on-premises Exchange Server.
• Microsoft 365 — Microsoft 365 is a service that includes various applications and services. It can include features like the Microsoft 365 Copilot app, which is designed for work, business, and education users.
• Copilot — Microsoft Copilot is a generative artificial intelligence chatbot developed by Microsoft AI. It is based on the Microsoft Prometheus large language model.
• Defender — Defender is a security software. In a historical context, it refers to a figure perceived as a defender of Slovak interests.
• Intune — Intune is a service that includes the Microsoft Intune Suite. It provides operational tools as well as security and automation features.