Anthropic reports service disruptions linked to microsoft 365 outage, followed by its own authentication issues

Anthropic has issued multiple status updates detailing service interruptions stemming from issues with Microsoft 365. The company reported that its connection to Microsoft 365 was experiencing elevated error rates and slow responses, affecting users attempting to access email, SharePoint, Teams chat, and calendars via the connector. Anthropic confirmed that the root cause was traced to an upstream service provider impacting the Microsoft 365 connector, which prevented most requests for email, calendar, and search functions from processing correctly. This disruption also affected Claude for Outlook, hindering email and calendar operations. Separately, Anthropic experienced its own service degradation. Earlier on November 13, 2026, the company confirmed that claude.ai, Claude Code, and platform.claude.com were all exhibiting abnormally high error rates, preventing users from successfully completing authentication on those platforms.