Global Microsoft 365 disruption affects Outlook and Teams calendar functions
As the service disruption persisted into Friday, Microsoft accelerated deployment of a broader fix while government email systems and Microsoft 365 integrations in ChatGPT and Claude experienced failures.
Outlook email services and several Teams capabilities remained impaired through Friday as a worldwide Microsoft 365 service disruption persisted.
In an update posted at 7:25 am UTC, Microsoft reported that a deployed patch had enhanced stability across certain servers and confirmed efforts were underway to expand the fix deployment. The status update, which was republished by the University of Pennsylvania, provided no specific timeline for complete service restoration.
Services first experienced disruption on Thursday, preventing certain users from gaining access to their Exchange Online mailboxes. According to Microsoft, a process responsible for managing secure connections experienced overload conditions, which resulted in affected servers ceasing to process incoming requests.
Microsoft detailed its restoration attempts, which included restarting infrastructure components, redirecting network traffic flows, and increasing server capacity. The company emphasized that no evidence suggested a security breach had occurred.
Additional services impacted by the disruption included certain capabilities within Microsoft Copilot and Defender for Office 365. Teams users encountered difficulties when attempting to schedule meetings and distribute invitations. According to Microsoft, the majority of Teams calling and chat functions remained operational.
Microsoft 365 serves as the primary email and scheduling platform for businesses and government agencies across the globe. In an October filing, Microsoft disclosed that the suite had surpassed 450 million paid commercial seats. Exchange Online provides the hosting infrastructure for mailboxes and calendars utilized by these organizations, while third-party applications, including AI assistants, depend on this same service to access that information when users link their work accounts.
ChatGPT's Microsoft 365 connector experienced errors, as reported by OpenAI. Anthropic confirmed that the service disruption resulted in the failure of most email, calendar, and search requests processed through Claude's Microsoft 365 connector.
The US Court of Appeals for the Tenth Circuit confirmed that its clerk's office experienced an inability to send or receive email throughout most of Thursday. On Friday, Japan's Finance Ministry reported being unable to receive email, and Singapore's Government Technology Agency confirmed to CNA that government email systems were included among the affected services.