Microsoft 365 global outage hits Outlook, Teams and Copilot
Starting November 12, Microsoft 365 experienced a widespread global service disruption affecting Outlook (web and client), Exchange Online, Teams, SharePoint Online, OneDrive and Microsoft 365 Copilot, with Americas users hit first—many unable to send or receive email or facing severe delays. Per Downdetector, by around 1:30 PM ET more than 120,000 users reported being unable to access Outlook, with thousands more reporting Teams failures.
Confirmed
- Microsoft officially attributed the incident to overloaded infrastructure components and core processes causing capacity loss, leading to connection errors.
- Recovery measures included isolating parts of the infrastructure, restarting affected components, shifting traffic and rebalancing resources, then gradually restoring traffic to verify stability.
Unconfirmed
- Per a tip relayed by @tomwarren, the root cause was a release/deployment that spiked server CPU usage and pushed racks into maintenance mode, triggering cascading failures; this comes from an internal leak—Microsoft's official account only confirmed overload-driven capacity loss.
Why it matters
- The incident swept across the entire Microsoft 365 suite; @ZealousidealPin3444 noted that AI assistants like Copilot went down along with the underlying services, highlighting how deeply coupled AI features and cloud infrastructure can become a single point of failure.
- @Kyrannio and @m4 both noted Americas Exchange Online users were hit first, showing how a regional infrastructure failure can quickly cascade into a global event.
2026-11-13 ~ 2026-11-13 · 6 related posts
Primary sources
- Microsoft Outlook down worldwide as M365 infrastructure buckles under load — tomwarren · 2026-11-13
- Microsoft 365, Teams, Copilot All Down at Once: Your AI Has One Big Off Switch — Zealousideal_Pin3444 · 2026-11-13
- [source] Microsoft 365 outage hits Exchange, Teams and Copilot across the Americas — Kyrannio · 2026-11-13
- Widespread Microsoft outage hits Outlook with 120,000+ user reports, Teams and Copilot also affected — asusarla · 2026-11-13
- [source] Microsoft Outlook outage: botched rollout spiked CPU, triggered cascading rack failures — tomwarren · 2026-11-13
- [source] Microsoft can't fix Outlook outage because engineers are getting too many Authenticator prompts — Kyrannio · 2026-11-13