Microsoft experienced a cascading software issue on Thursday that knocked out Outlook email, Teams video conferencing, Copilot AI, Defender security screening, Intune dashboards, and cloud‑based Windows PCs, affecting both consumer and business services worldwide. Engineers reported that a large number of servers became unexpectedly unavailable, leading to roughly 18 hours of downtime before traffic began returning on Friday morning on the U.S. east coast.
The outage exposed a single point of failure in Microsoft’s cloud infrastructure, raising concerns for enterprises that rely on its services for critical communication and security. Prolonged loss of email and AI tools can disrupt business operations, increase churn risk, and prompt customers to evaluate multi‑cloud strategies.